diff --git a/Makefile b/Makefile
index 8d8dcac..faa81d1 100644
--- a/Makefile
+++ b/Makefile
@@ -40,7 +40,7 @@ bin/%.o: src/%.c
 bin/lib/%.o: src/lib/%.c
 	$(CC) -c -o $@ $(CFLAGS) $<
 
-bin/sesimos: bin/server.o bin/client.o \
+bin/sesimos: bin/server.o bin/client.o bin/logger.o \
 			 bin/lib/cache.o bin/lib/compress.o bin/lib/config.o bin/lib/fastcgi.o bin/lib/geoip.o \
 			 bin/lib/http.o bin/lib/http_static.o bin/lib/rev_proxy.o bin/lib/sock.o bin/lib/uri.o \
 		     bin/lib/utils.o bin/lib/websocket.o
@@ -48,26 +48,28 @@ bin/sesimos: bin/server.o bin/client.o \
 
 
 bin/server.o: src/server.h src/defs.h src/client.h src/lib/cache.h src/lib/config.h src/lib/sock.h \
-              src/lib/rev_proxy.h src/lib/geoip.h src/lib/utils.h
+              src/lib/rev_proxy.h src/lib/geoip.h src/lib/utils.h src/logger.h
 
 bin/client.o: src/client.h src/defs.h src/server.h src/lib/utils.h src/lib/config.h src/lib/sock.h \
               src/lib/http.h src/lib/rev_proxy.h src/lib/fastcgi.h src/lib/cache.h src/lib/geoip.h src/lib/compress.h \
-              src/lib/websocket.h
+              src/lib/websocket.h src/logger.h
 
-bin/lib/cache.o: src/lib/cache.h src/lib/utils.h src/lib/uri.h src/lib/compress.h
+bin/logger.o: src/logger.h
+
+bin/lib/cache.o: src/lib/cache.h src/lib/utils.h src/lib/uri.h src/lib/compress.h src/logger.h
 
 bin/lib/compress.o: src/lib/compress.h
 
-bin/lib/config.o: src/lib/config.h src/lib/utils.h src/lib/uri.h
+bin/lib/config.o: src/lib/config.h src/lib/utils.h src/lib/uri.h src/logger.h
 
 bin/lib/fastcgi.o: src/lib/fastcgi.h src/server.h src/lib/utils.h src/lib/compress.h src/lib/http.h \
-                   src/lib/uri.h src/lib/include/fastcgi.h
+                   src/lib/uri.h src/lib/include/fastcgi.h src/logger.h
 
 bin/lib/geoip.o: src/lib/geoip.h
 
-bin/lib/http.o: src/lib/http.h src/lib/utils.h src/lib/compress.h src/lib/sock.h
+bin/lib/http.o: src/lib/http.h src/lib/utils.h src/lib/compress.h src/lib/sock.h src/logger.h
 
-bin/lib/rev_proxy.o: src/lib/rev_proxy.h src/defs.h src/server.h src/lib/compress.h
+bin/lib/rev_proxy.o: src/lib/rev_proxy.h src/defs.h src/server.h src/lib/compress.h src/logger.h
 
 bin/lib/sock.o: src/lib/sock.h
 
@@ -75,7 +77,7 @@ bin/lib/uri.o: src/lib/uri.h src/lib/utils.h
 
 bin/lib/utils.o: src/lib/utils.h
 
-bin/lib/websocket.o: src/lib/websocket.h src/defs.h src/lib/utils.h src/lib/sock.h
+bin/lib/websocket.o: src/lib/websocket.h src/defs.h src/lib/utils.h src/lib/sock.h src/logger.h
 
 
 permit:
diff --git a/src/client.c b/src/client.c
index 145bd24..9608145 100644
--- a/src/client.c
+++ b/src/client.c
@@ -9,6 +9,7 @@
 #include "defs.h"
 #include "client.h"
 #include "server.h"
+#include "logger.h"
 
 #include "lib/utils.h"
 #include "lib/config.h"
@@ -141,13 +142,13 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
         strcpy(host, host_ptr);
     }
 
-    sprintf(log_req_prefix, "[%6i][%s%*s%s]%s ", getpid(), BLD_STR, INET6_ADDRSTRLEN, host, CLR_STR, log_client_prefix);
-    log_prefix = log_req_prefix;
-    print(BLD_STR "%s %s" CLR_STR, req.method, req.uri);
+    sprintf(log_req_prefix, "[%6i][%s%*s%s]%s", getpid(), BLD_STR, INET6_ADDRSTRLEN, host, CLR_STR, log_client_prefix);
+    logger_set_prefix(log_req_prefix);
+    info(BLD_STR "%s %s", req.method, req.uri);
 
     conf = get_host_config(host);
     if (conf == NULL) {
-        print("Unknown host, redirecting to default");
+        info("Unknown host, redirecting to default");
         res.status = http_get_status(307);
         sprintf(buf0, "https://%s%s", DEFAULT_HOST, req.uri);
         http_add_header_field(&res.hdr, "Location", buf0);
@@ -184,7 +185,7 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
                 p_len = snprintf(buf1, sizeof(buf1), "https://%s%s", host, buf0);
                 if (p_len < 0 || p_len >= sizeof(buf1)) {
                     res.status = http_get_status(500);
-                    print(ERR_STR "Header field 'Location' too long" CLR_STR);
+                    error("Header field 'Location' too long");
                     goto respond;
                 }
                 http_add_header_field(&res.hdr, "Location", buf1);
@@ -373,7 +374,7 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
                 mode = FASTCGI_PHP;
             } else {
                 res.status = http_get_status(500);
-                print(ERR_STR "Invalid FastCGI extension: %s" CLR_STR, uri.filename);
+                error("Invalid FastCGI extension: %s", uri.filename);
                 goto respond;
             }
 
@@ -475,7 +476,7 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
             }
         }
     } else if (conf->type == CONFIG_TYPE_REVERSE_PROXY) {
-        print("Reverse proxy for " BLD_STR "%s:%i" CLR_STR, conf->rev_proxy.hostname, conf->rev_proxy.port);
+        info("Reverse proxy for " BLD_STR "%s:%i" CLR_STR, conf->rev_proxy.hostname, conf->rev_proxy.port);
         http_remove_header_field(&res.hdr, "Date", HTTP_REMOVE_ALL);
         http_remove_header_field(&res.hdr, "Server", HTTP_REMOVE_ALL);
 
@@ -542,7 +543,7 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
         }
         */
     } else {
-        print(ERR_STR "Unknown host type: %i" CLR_STR, conf->type);
+        error("Unknown host type: %i", conf->type);
         res.status = http_get_status(501);
     }
 
@@ -637,21 +638,21 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
     clock_gettime(CLOCK_MONOTONIC, &end);
     const char *location = http_get_header_field(&res.hdr, "Location");
     unsigned long micros = (end.tv_nsec - begin.tv_nsec) / 1000 + (end.tv_sec - begin.tv_sec) * 1000000;
-    print("%s%s%03i %s%s%s (%s)%s", http_get_status_color(res.status), use_rev_proxy ? "-> " : "", res.status->code,
-          res.status->msg, location != NULL ? " -> " : "", location != NULL ? location : "",
-          format_duration(micros, buf0), CLR_STR);
+    info("%s%s%03i %s%s%s (%s)%s", http_get_status_color(res.status), use_rev_proxy ? "-> " : "", res.status->code,
+         res.status->msg, location != NULL ? " -> " : "", location != NULL ? location : "",
+         format_duration(micros, buf0), CLR_STR);
 
     // TODO access/error log file
 
     if (use_rev_proxy == 2) {
         // WebSocket
-        print("Upgrading connection to WebSocket connection");
+        info("Upgrading connection to WebSocket connection");
         ret = ws_handle_connection(client, &rev_proxy);
         if (ret != 0) {
             client_keep_alive = 0;
             close_proxy = 1;
         }
-        print("WebSocket connection closed");
+        info("WebSocket connection closed");
     } else if (strcmp(req.method, "HEAD") != 0) {
         // default response
         unsigned long snd_len = 0;
@@ -659,7 +660,7 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
         if (msg_buf[0] != 0) {
             ret = sock_send(client, msg_buf, content_length, 0);
             if (ret <= 0) {
-                print(ERR_STR "Unable to send: %s" CLR_STR, sock_strerror(client));
+                error("Unable to send: %s", sock_strerror(client));
             }
             snd_len += ret;
         } else if (file != NULL) {
@@ -670,7 +671,7 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
                 }
                 ret = sock_send(client, buffer, len, feof(file) ? 0 : MSG_MORE);
                 if (ret <= 0) {
-                    print(ERR_STR "Unable to send: %s" CLR_STR, sock_strerror(client));
+                    error("Unable to send: %s", sock_strerror(client));
                     break;
                 }
                 snd_len += ret;
@@ -701,13 +702,13 @@ int client_request_handler(sock *client, unsigned long client_num, unsigned int
     }
 
     if (close_proxy && rev_proxy.socket != 0) {
-        print(BLUE_STR "Closing proxy connection" CLR_STR);
+        info(BLUE_STR "Closing proxy connection");
         sock_close(&rev_proxy);
     }
 
     clock_gettime(CLOCK_MONOTONIC, &end);
     micros = (end.tv_nsec - begin.tv_nsec) / 1000 + (end.tv_sec - begin.tv_sec) * 1000000;
-    print("Transfer complete: %s", format_duration(micros, buf0));
+    info("Transfer complete: %s", format_duration(micros, buf0));
 
     uri_free(&uri);
     abort:
@@ -732,13 +733,13 @@ int client_connection_handler(sock *client, unsigned long client_num) {
         sprintf(buf, "dig @%s +short +time=1 -x %s", dns_server, client_addr_str);
         FILE *dig = popen(buf, "r");
         if (dig == NULL) {
-            print(ERR_STR "Unable to start dig: %s" CLR_STR "\n", strerror(errno));
+            error("Unable to start dig: %s", strerror(errno));
             goto dig_err;
         }
         unsigned long read = fread(buf, 1, sizeof(buf), dig);
         ret = pclose(dig);
         if (ret != 0) {
-            print(ERR_STR "Dig terminated with exit code %i" CLR_STR "\n", ret);
+            error("Dig terminated with exit code %i", ret);
             goto dig_err;
         }
         char *ptr = memchr(buf, '\n', read);
@@ -759,10 +760,10 @@ int client_connection_handler(sock *client, unsigned long client_num) {
         int gai_error, mmdb_res;
         MMDB_lookup_result_s result = MMDB_lookup_string(&mmdbs[i], client_addr_str, &gai_error, &mmdb_res);
         if (mmdb_res != MMDB_SUCCESS) {
-            print(ERR_STR "Unable to lookup geoip info: %s" CLR_STR "\n", MMDB_strerror(mmdb_res));
+            error("Unable to lookup geoip info: %s", MMDB_strerror(mmdb_res));
             continue;
         } else if (gai_error != 0) {
-            print(ERR_STR "Unable to lookup geoip info" CLR_STR "\n");
+            error("Unable to lookup geoip info");
             continue;
         } else if (!result.found_entry) {
             continue;
@@ -771,7 +772,7 @@ int client_connection_handler(sock *client, unsigned long client_num) {
         MMDB_entry_data_list_s *list;
         mmdb_res = MMDB_get_entry_data_list(&result.entry, &list);
         if (mmdb_res != MMDB_SUCCESS) {
-            print(ERR_STR "Unable to lookup geoip info: %s" CLR_STR "\n", MMDB_strerror(mmdb_res));
+            error("Unable to lookup geoip info: %s", MMDB_strerror(mmdb_res));
             continue;
         }
 
@@ -802,9 +803,9 @@ int client_connection_handler(sock *client, unsigned long client_num) {
         }
     }
 
-    print("Connection accepted from %s %s%s%s[%s]", client_addr_str, client_host_str != NULL ? "(" : "",
-          client_host_str != NULL ? client_host_str : "", client_host_str != NULL ? ") " : "",
-          client_cc[0] != 0 ? client_cc : "N/A");
+    info("Connection accepted from %s %s%s%s[%s]", client_addr_str, client_host_str != NULL ? "(" : "",
+         client_host_str != NULL ? client_host_str : "", client_host_str != NULL ? ") " : "",
+         client_cc[0] != 0 ? client_cc : "N/A");
 
     client_timeout.tv_sec = CLIENT_TIMEOUT;
     client_timeout.tv_usec = 0;
@@ -812,7 +813,7 @@ int client_connection_handler(sock *client, unsigned long client_num) {
         goto set_timeout_err;
     if (setsockopt(client->socket, SOL_SOCKET, SO_SNDTIMEO, &client_timeout, sizeof(client_timeout)) < 0) {
         set_timeout_err:
-        print(ERR_STR "Unable to set timeout for socket: %s" CLR_STR, strerror(errno));
+        error("Unable to set timeout for socket");
         return 1;
     }
 
@@ -826,7 +827,7 @@ int client_connection_handler(sock *client, unsigned long client_num) {
         client->_errno = errno;
         client->_ssl_error = ERR_get_error();
         if (ret <= 0) {
-            print(ERR_STR "Unable to perform handshake: %s" CLR_STR, sock_strerror(client));
+            error("Unable to perform handshake: %s", sock_strerror(client));
             ret = -1;
             goto close;
         }
@@ -836,21 +837,21 @@ int client_connection_handler(sock *client, unsigned long client_num) {
     ret = 0;
     while (ret == 0 && server_keep_alive && req_num < REQ_PER_CONNECTION) {
         ret = client_request_handler(client, client_num, req_num++);
-        log_prefix = log_conn_prefix;
+        logger_set_prefix(log_conn_prefix);
     }
 
     close:
     sock_close(client);
 
     if (rev_proxy.socket != 0) {
-        print(BLUE_STR "Closing proxy connection" CLR_STR);
+        info(BLUE_STR "Closing proxy connection");
         sock_close(&rev_proxy);
     }
 
     clock_gettime(CLOCK_MONOTONIC, &end);
     unsigned long micros = (end.tv_nsec - begin.tv_nsec) / 1000 + (end.tv_sec - begin.tv_sec) * 1000000;
 
-    print("Connection closed (%s)", format_duration(micros, buf));
+    info("Connection closed (%s)", format_duration(micros, buf));
     return 0;
 }
 
@@ -890,10 +891,10 @@ int client_handler(sock *client, unsigned long client_num, struct sockaddr_in6 *
             ntohs(client_addr->sin6_port), CLR_STR);
 
     log_conn_prefix = malloc(256);
-    sprintf(log_conn_prefix, "[%6i][%*s]%s ", getpid(), INET6_ADDRSTRLEN, server_addr_str, log_client_prefix);
-    log_prefix = log_conn_prefix;
+    sprintf(log_conn_prefix, "[%6i][%*s]%s", getpid(), INET6_ADDRSTRLEN, server_addr_str, log_client_prefix);
+    logger_set_prefix(log_conn_prefix);
 
-    print("Started child process with PID %i", getpid());
+    info("Started child process with PID %i", getpid());
 
     ret = client_connection_handler(client, client_num);
 
diff --git a/src/lib/cache.c b/src/lib/cache.c
index 5acadda..468d99f 100644
--- a/src/lib/cache.c
+++ b/src/lib/cache.c
@@ -6,6 +6,7 @@
  * @date 2020-12-19
  */
 
+#include "../logger.h"
 #include "cache.h"
 #include "utils.h"
 #include "compress.h"
@@ -27,11 +28,11 @@ cache_entry *cache;
 int magic_init(void) {
     magic = magic_open(MAGIC_MIME);
     if (magic == NULL) {
-        fprintf(stderr, ERR_STR "Unable to open magic cookie: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to open magic cookie");
         return -1;
     }
     if (magic_load(magic, CACHE_MAGIC_FILE) != 0) {
-        fprintf(stderr, ERR_STR "Unable to load magic cookie: %s" CLR_STR "\n", magic_error(magic));
+        critical("Unable to load magic cookie: %s", magic_error(magic));
         return -2;
     }
     return 0;
@@ -42,30 +43,34 @@ void cache_process_term(int _) {
 }
 
 int cache_process(void) {
+    errno = 0;
     signal(SIGINT, cache_process_term);
     signal(SIGTERM, cache_process_term);
 
+    logger_set_name("cache");
+
     int shm_id = shmget(CACHE_SHM_KEY, CACHE_ENTRIES * sizeof(cache_entry), 0);
     if (shm_id < 0) {
-        fprintf(stderr, ERR_STR "Unable to create cache shared memory: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create cache shared memory");
         return -1;
     }
 
     shmdt(cache);
+    errno = 0;
     void *shm_rw = shmat(shm_id, NULL, 0);
     if (shm_rw == (void *) -1) {
-        fprintf(stderr, ERR_STR "Unable to attach cache shared memory (rw): %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to attach cache shared memory (rw)");
         return -2;
     }
     cache = shm_rw;
 
     if (mkdir("/var/sesimos/", 0755) < 0 && errno != EEXIST) {
-        fprintf(stderr, ERR_STR "Unable to create directory '/var/sesimos/': %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create directory '/var/sesimos/'");
         return -3;
     }
 
     if (mkdir("/var/sesimos/server/", 0755) < 0 && errno != EEXIST) {
-        fprintf(stderr, ERR_STR "Unable to create directory '/var/sesimos/server/': %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create directory '/var/sesimos/server/'");
         return -3;
     }
 
@@ -75,6 +80,8 @@ int cache_process(void) {
         fclose(cache_file);
     }
 
+    errno = 0;
+
     for (int i = 0; i < CACHE_ENTRIES; i++) {
         cache[i].is_updating = 0;
     }
@@ -93,7 +100,7 @@ int cache_process(void) {
         for (int i = 0; i < CACHE_ENTRIES; i++) {
             if (cache[i].filename[0] != 0 && cache[i].meta.etag[0] == 0 && !cache[i].is_updating) {
                 cache[i].is_updating = 1;
-                fprintf(stdout, "[cache] Hashing file %s\n", cache[i].filename);
+                info("Hashing file %s", cache[i].filename);
 
                 ctx = EVP_MD_CTX_new();
                 EVP_DigestInit(ctx, EVP_sha1());
@@ -106,15 +113,16 @@ int cache_process(void) {
                 if (compress) {
                     sprintf(buf, "%.*s/.sesimos", cache[i].webroot_len, cache[i].filename);
                     if (mkdir(buf, 0755) != 0 && errno != EEXIST) {
-                        fprintf(stderr, ERR_STR "Unable to create directory %s: %s" CLR_STR "\n", buf, strerror(errno));
+                        error("Unable to create directory %s", buf);
                         goto comp_err;
                     }
 
                     sprintf(buf, "%.*s/.sesimos/cache", cache[i].webroot_len, cache[i].filename);
                     if (mkdir(buf, 0700) != 0 && errno != EEXIST) {
-                        fprintf(stderr, ERR_STR "Unable to create directory %s: %s" CLR_STR "\n", buf, strerror(errno));
+                        error("Unable to create directory %s", buf);
                         goto comp_err;
                     }
+                    errno = 0;
 
                     char *rel_path = cache[i].filename + cache[i].webroot_len + 1;
                     for (int j = 0; j < strlen(rel_path); j++) {
@@ -131,22 +139,22 @@ int cache_process(void) {
                                         "%.*s/.sesimos/cache/%s.br",
                                         cache[i].webroot_len, cache[i].filename, buf);
                     if (p_len_gz < 0 || p_len_gz >= sizeof(filename_comp_gz) || p_len_br < 0 || p_len_br >= sizeof(filename_comp_br)) {
-                        fprintf(stderr, ERR_STR "Unable to open cached file: File name for compressed file too long" CLR_STR "\n");
+                        error("Unable to open cached file: File name for compressed file too long");
                         goto comp_err;
                     }
 
-                    fprintf(stdout, "[cache] Compressing file %s\n", cache[i].filename);
+                    info("Compressing file %s", cache[i].filename);
 
                     comp_file_gz = fopen(filename_comp_gz, "wb");
                     comp_file_br = fopen(filename_comp_br, "wb");
                     if (comp_file_gz == NULL || comp_file_br == NULL) {
-                        fprintf(stderr, ERR_STR "Unable to open cached file: %s" CLR_STR "\n", strerror(errno));
+                        error("Unable to open cached file");
                         comp_err:
                         compress = 0;
                     } else {
                         ret = compress_init(&comp_ctx, COMPRESS_GZ | COMPRESS_BR);
                         if (ret != 0) {
-                            fprintf(stderr, ERR_STR "Unable to init compression: %s" CLR_STR "\n", strerror(errno));
+                            error("Unable to init compression");
                             compress = 0;
                             fclose(comp_file_gz);
                             fclose(comp_file_br);
@@ -177,7 +185,7 @@ int cache_process(void) {
                     compress_free(&comp_ctx);
                     fclose(comp_file_gz);
                     fclose(comp_file_br);
-                    fprintf(stdout, "[cache] Finished compressing file %s\n", cache[i].filename);
+                    info("Finished compressing file %s", cache[i].filename);
                     strcpy(cache[i].meta.filename_comp_gz, filename_comp_gz);
                     strcpy(cache[i].meta.filename_comp_br, filename_comp_br);
                 } else {
@@ -193,7 +201,7 @@ int cache_process(void) {
                     sprintf(cache[i].meta.etag + j * 2, "%02x", hash[j]);
                 }
                 fclose(file);
-                fprintf(stdout, "[cache] Finished hashing file %s\n", cache[i].filename);
+                info("Finished hashing file %s", cache[i].filename);
                 cache[i].is_updating = 0;
                 cache_changed = 1;
             }
@@ -203,7 +211,7 @@ int cache_process(void) {
             cache_changed = 0;
             cache_file = fopen("/var/sesimos/server/cache", "wb");
             if (cache_file == NULL) {
-                fprintf(stderr, ERR_STR "Unable to open cache file: %s" CLR_STR "\n", strerror(errno));
+                critical("Unable to open cache file");
                 return -1;
             }
             fwrite(cache, sizeof(cache_entry), CACHE_ENTRIES, cache_file);
@@ -217,32 +225,34 @@ int cache_process(void) {
 }
 
 int cache_init(void) {
+    errno = 0;
     if (magic_init() != 0) {
         return -1;
     }
 
     int shm_id = shmget(CACHE_SHM_KEY, CACHE_ENTRIES * sizeof(cache_entry), IPC_CREAT | IPC_EXCL | 0600);
     if (shm_id < 0) {
-        fprintf(stderr, ERR_STR "Unable to create cache shared memory: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create cache shared memory");
         return -2;
     }
 
     void *shm = shmat(shm_id, NULL, SHM_RDONLY);
     if (shm == (void *) -1) {
-        fprintf(stderr, ERR_STR "Unable to attach cache shared memory (ro): %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to attach cache shared memory (ro)");
         return -3;
     }
     cache = shm;
 
     void *shm_rw = shmat(shm_id, NULL, 0);
     if (shm_rw == (void *) -1) {
-        fprintf(stderr, ERR_STR "Unable to attach cache shared memory (rw): %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to attach cache shared memory (rw)");
         return -4;
     }
     cache = shm_rw;
     memset(cache, 0, CACHE_ENTRIES * sizeof(cache_entry));
     shmdt(shm_rw);
     cache = shm;
+    errno = 0;
 
     pid_t pid = fork();
     if (pid == 0) {
@@ -254,10 +264,10 @@ int cache_init(void) {
         }
     } else if (pid > 0) {
         // parent
-        fprintf(stderr, "Started child process with PID %i as cache-updater\n", pid);
+        info("Started child process with PID %i as cache-updater", pid);
         return pid;
     } else {
-        fprintf(stderr, ERR_STR "Unable to create child process: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create child process");
         return -5;
     }
 }
@@ -265,15 +275,16 @@ int cache_init(void) {
 int cache_unload(void) {
     int shm_id = shmget(CACHE_SHM_KEY, 0, 0);
     if (shm_id < 0) {
-        fprintf(stderr, ERR_STR "Unable to get cache shared memory id: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to get cache shared memory id");
         shmdt(cache);
         return -1;
     } else if (shmctl(shm_id, IPC_RMID, NULL) < 0) {
-        fprintf(stderr, ERR_STR "Unable to configure cache shared memory: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to configure cache shared memory");
         shmdt(cache);
         return -1;
     }
     shmdt(cache);
+    errno = 0;
     return 0;
 }
 
@@ -282,7 +293,7 @@ int cache_update_entry(int entry_num, const char *filename, const char *webroot)
     int shm_id = shmget(CACHE_SHM_KEY, 0, 0);
     void *shm_rw = shmat(shm_id, NULL, 0);
     if (shm_rw == (void *) -1) {
-        print(ERR_STR "Unable to attach cache shared memory (rw): %s" CLR_STR, strerror(errno));
+        error("Unable to attach cache shared memory (rw)");
         return -1;
     }
     cache = shm_rw;
@@ -317,6 +328,7 @@ int cache_update_entry(int entry_num, const char *filename, const char *webroot)
 
     shmdt(shm_rw);
     cache = cache_ro;
+    errno = 0;
     return 0;
 }
 
@@ -325,7 +337,7 @@ int cache_filename_comp_invalid(const char *filename) {
     int shm_id = shmget(CACHE_SHM_KEY, 0, 0);
     void *shm_rw = shmat(shm_id, NULL, 0);
     if (shm_rw == (void *) -1) {
-        print(ERR_STR "Unable to attach cache shared memory (rw): %s" CLR_STR, strerror(errno));
+        error("Unable to attach cache shared memory (rw)");
         return -1;
     }
     cache = shm_rw;
diff --git a/src/lib/config.c b/src/lib/config.c
index 79cfb79..50db665 100644
--- a/src/lib/config.c
+++ b/src/lib/config.c
@@ -6,6 +6,7 @@
  * @date 2021-01-05
  */
 
+#include "../logger.h"
 #include "config.h"
 #include "utils.h"
 
@@ -23,20 +24,20 @@ char geoip_dir[256], dns_server[256];
 int config_init(void) {
     int shm_id = shmget(CONFIG_SHM_KEY, sizeof(t_config), IPC_CREAT | IPC_EXCL | 0640);
     if (shm_id < 0) {
-        fprintf(stderr, ERR_STR "Unable to create config shared memory: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create config shared memory");
         return -1;
     }
 
     void *shm = shmat(shm_id, NULL, SHM_RDONLY);
     if (shm == (void *) -1) {
-        fprintf(stderr, ERR_STR "Unable to attach config shared memory (ro): %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to attach config shared memory (ro)");
         return -2;
     }
     config = shm;
 
     void *shm_rw = shmat(shm_id, NULL, 0);
     if (shm_rw == (void *) -1) {
-        fprintf(stderr, ERR_STR "Unable to attach config shared memory (rw): %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to attach config shared memory (rw)");
         return -3;
     }
     config = shm_rw;
@@ -49,11 +50,11 @@ int config_init(void) {
 int config_unload(void) {
     int shm_id = shmget(CONFIG_SHM_KEY, 0, 0);
     if (shm_id < 0) {
-        fprintf(stderr, ERR_STR "Unable to get config shared memory id: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to get config shared memory id");
         shmdt(config);
         return -1;
     } else if (shmctl(shm_id, IPC_RMID, NULL) < 0) {
-        fprintf(stderr, ERR_STR "Unable to configure config shared memory: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to configure config shared memory");
         shmdt(config);
         return -1;
     }
@@ -64,7 +65,7 @@ int config_unload(void) {
 int config_load(const char *filename) {
     FILE *file = fopen(filename, "r");
     if (file == NULL) {
-        fprintf(stderr, ERR_STR "Unable to open config file: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to open config file");
         return -1;
     }
 
@@ -211,7 +212,7 @@ int config_load(const char *filename) {
         if (strlen(source) == 0) {
             err:
             free(tmp_config);
-            fprintf(stderr, ERR_STR "Unable to parse config file (line %i)" CLR_STR "\n", line);
+            critical("Unable to parse config file (line %i)", line);
             return -2;
         }
 
@@ -252,14 +253,14 @@ int config_load(const char *filename) {
         if (!found) {
             err2:
             free(tmp_config);
-            fprintf(stderr, ERR_STR "Unable to parse config file" CLR_STR "\n");
+            critical("Unable to parse config file");
             return -2;
         }
     }
 
     int shm_id = shmget(CONFIG_SHM_KEY, 0, 0);
     if (shm_id < 0) {
-        fprintf(stderr, ERR_STR "Unable to get config shared memory id: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to get config shared memory id");
         shmdt(config);
         return -3;
     }
@@ -267,7 +268,7 @@ int config_load(const char *filename) {
     void *shm_rw = shmat(shm_id, NULL, 0);
     if (shm_rw == (void *) -1) {
         free(tmp_config);
-        fprintf(stderr, ERR_STR "Unable to attach config shared memory (rw): %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to attach config shared memory (rw)");
         return -4;
     }
     memcpy(shm_rw, tmp_config, sizeof(t_config));
diff --git a/src/lib/fastcgi.c b/src/lib/fastcgi.c
index 402a81d..a9a91b9 100644
--- a/src/lib/fastcgi.c
+++ b/src/lib/fastcgi.c
@@ -10,6 +10,7 @@
 #include "utils.h"
 #include "compress.h"
 #include "../server.h"
+#include "../logger.h"
 
 #include <sys/un.h>
 #include <sys/socket.h>
@@ -68,7 +69,7 @@ int fastcgi_init(fastcgi_conn *conn, int mode, unsigned int client_num, unsigned
 
     int fcgi_sock = socket(AF_UNIX, SOCK_STREAM, 0);
     if (fcgi_sock < 0) {
-        print(ERR_STR "Unable to create unix socket: %s" CLR_STR, strerror(errno));
+        error("Unable to create unix socket");
         return -1;
     }
     conn->socket = fcgi_sock;
@@ -81,7 +82,7 @@ int fastcgi_init(fastcgi_conn *conn, int mode, unsigned int client_num, unsigned
     }
 
     if (connect(conn->socket, (struct sockaddr *) &sock_addr, sizeof(sock_addr)) < 0) {
-        print(ERR_STR "Unable to connect to unix socket of FastCGI socket: %s" CLR_STR, strerror(errno));
+        error("Unable to connect to unix socket of FastCGI socket");
         return -1;
     }
 
@@ -101,7 +102,7 @@ int fastcgi_init(fastcgi_conn *conn, int mode, unsigned int client_num, unsigned
             {.roleB1 = (FCGI_RESPONDER >> 8) & 0xFF, .roleB0 = FCGI_RESPONDER & 0xFF, .flags = 0}
     };
     if (send(conn->socket, &begin, sizeof(begin), 0) != sizeof(begin)) {
-        print(ERR_STR "Unable to send to FastCGI socket: %s" CLR_STR, strerror(errno));
+        error("Unable to send to FastCGI socket");
         return -2;
     }
 
@@ -186,7 +187,7 @@ int fastcgi_init(fastcgi_conn *conn, int mode, unsigned int client_num, unsigned
     header.contentLengthB0 = param_len & 0xFF;
     memcpy(param_buf, &header, sizeof(header));
     if (send(conn->socket, param_buf, param_len + sizeof(header), 0) != param_len + sizeof(header)) {
-        print(ERR_STR "Unable to send to FastCGI socket: %s" CLR_STR, strerror(errno));
+        error("Unable to send to FastCGI socket");
         return -2;
     }
 
@@ -194,7 +195,7 @@ int fastcgi_init(fastcgi_conn *conn, int mode, unsigned int client_num, unsigned
     header.contentLengthB1 = 0;
     header.contentLengthB0 = 0;
     if (send(conn->socket, &header, sizeof(header), 0) != sizeof(header)) {
-        print(ERR_STR "Unable to send to FastCGI socket: %s" CLR_STR, strerror(errno));
+        error("Unable to send to FastCGI socket");
         return -2;
     }
 
@@ -214,7 +215,7 @@ int fastcgi_close_stdin(fastcgi_conn *conn) {
     };
 
     if (send(conn->socket, &header, sizeof(header), 0) != sizeof(header)) {
-        print(ERR_STR "Unable to send to FastCGI socket: %s" CLR_STR, strerror(errno));
+        error("Unable to send to FastCGI socket");
         return -2;
     }
 
@@ -231,7 +232,7 @@ int fastcgi_php_error(const fastcgi_conn *conn, const char *msg, int msg_len, ch
     int err = 0;
     // FIXME *msg is part of a stream, handle fragmented lines
     while (1) {
-        int msg_type = 0;
+        log_lvl_t msg_type = LOG_INFO;
         int msg_pre_len = 0;
         ptr1 = strstr(ptr0, "PHP message: ");
         if (ptr1 == NULL) {
@@ -245,16 +246,16 @@ int fastcgi_php_error(const fastcgi_conn *conn, const char *msg, int msg_len, ch
         }
 
         if (len >= 14 && strncmp(ptr0, "PHP Warning:  ", 14) == 0) {
-            msg_type = 1;
+            msg_type = LOG_WARNING;
             msg_pre_len = 14;
         } else if (len >= 18 && strncmp(ptr0, "PHP Fatal error:  ", 18) == 0) {
-            msg_type = 2;
+            msg_type = LOG_ERROR;
             msg_pre_len = 18;
         } else if (len >= 18 && strncmp(ptr0, "PHP Parse error:  ", 18) == 0) {
-            msg_type = 2;
+            msg_type = LOG_ERROR;
             msg_pre_len = 18;
         } else if (len >= 18 && strncmp(ptr0, "PHP Notice:  ", 13) == 0) {
-            msg_type = 1;
+            msg_type = LOG_NOTICE;
             msg_pre_len = 13;
         }
 
@@ -267,7 +268,7 @@ int fastcgi_php_error(const fastcgi_conn *conn, const char *msg, int msg_len, ch
             if (ptr3 != NULL && (ptr3 - ptr2) < len2) {
                 len2 = (int) (ptr3 - ptr2);
             }
-            print("%s%.*s%s", msg_type == 1 ? WRN_STR : msg_type == 2 ? ERR_STR : "", len2, ptr2, CLR_STR);
+            logmsgf(msg_type, "%.*s", len2, ptr2);
             if (msg_type == 2 && ptr2 == ptr0) {
                 strcpy_rem_webroot(err_msg, ptr2, len2, conn->webroot);
                 err = 1;
@@ -300,12 +301,12 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
         if (ret < 0) {
             res->status = http_get_status(500);
             sprintf(err_msg, "Unable to communicate with FastCGI socket.");
-            print(ERR_STR "Unable to receive from FastCGI socket: %s" CLR_STR, strerror(errno));
+            error("Unable to receive from FastCGI socket");
             return 1;
         } else if (ret != sizeof(header)) {
             res->status = http_get_status(500);
             sprintf(err_msg, "Unable to communicate with FastCGI socket.");
-            print(ERR_STR "Unable to receive from FastCGI socket" CLR_STR);
+            error("Unable to receive from FastCGI socket");
             return 1;
         }
         req_id = (header.requestIdB1 << 8) | header.requestIdB0;
@@ -315,13 +316,13 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
         if (ret < 0) {
             res->status = http_get_status(500);
             sprintf(err_msg, "Unable to communicate with FastCGI socket.");
-            print(ERR_STR "Unable to receive from FastCGI socket: %s" CLR_STR, strerror(errno));
+            error("Unable to receive from FastCGI socket");
             free(content);
             return 1;
         } else if (ret != (content_len + header.paddingLength)) {
             res->status = http_get_status(500);
             sprintf(err_msg, "Unable to communicate with FastCGI socket.");
-            print(ERR_STR "Unable to receive from FastCGI socket" CLR_STR);
+            error("Unable to receive from FastCGI socket");
             free(content);
             return 1;
         }
@@ -335,10 +336,10 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
             int app_status = (body->appStatusB3 << 24) | (body->appStatusB2 << 16) | (body->appStatusB1 << 8) |
                              body->appStatusB0;
             if (body->protocolStatus != FCGI_REQUEST_COMPLETE) {
-                print(ERR_STR "FastCGI protocol error: %i" CLR_STR, body->protocolStatus);
+                error("FastCGI protocol error: %i", body->protocolStatus);
             }
             if (app_status != 0) {
-                print(ERR_STR "FastCGI app terminated with exit code %i" CLR_STR, app_status);
+                error("FastCGI app terminated with exit code %i", app_status);
             }
             close(conn->socket);
             conn->socket = 0;
@@ -352,7 +353,7 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
         } else if (header.type == FCGI_STDOUT) {
             break;
         } else {
-            print(ERR_STR "Unknown FastCGI type: %i" CLR_STR, header.type);
+            error("Unknown FastCGI type: %i", header.type);
         }
 
         free(content);
@@ -369,13 +370,13 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
     char *buf = content;
     unsigned short header_len = conn->out_off;
     if (header_len <= 0) {
-        print(ERR_STR "Unable to parse header: End of header not found" CLR_STR);
+        error("Unable to parse header: End of header not found");
         return 1;
     }
 
     for (int i = 0; i < header_len; i++) {
         if ((buf[i] >= 0x00 && buf[i] <= 0x1F && buf[i] != '\r' && buf[i] != '\n') || buf[i] == 0x7F) {
-            print(ERR_STR "Unable to parse header: Header contains illegal characters" CLR_STR);
+            error("Unable to parse header: Header contains illegal characters");
             return 2;
         }
     }
@@ -384,7 +385,7 @@ int fastcgi_header(fastcgi_conn *conn, http_res *res, char *err_msg) {
     while (header_len != (ptr - buf)) {
         char *pos0 = strstr(ptr, "\r\n");
         if (pos0 == NULL) {
-            print(ERR_STR "Unable to parse header: Invalid header format" CLR_STR);
+            error("Unable to parse header: Invalid header format");
             return 1;
         }
 
@@ -413,13 +414,13 @@ int fastcgi_send(fastcgi_conn *conn, sock *client, int flags) {
     if (flags & FASTCGI_COMPRESS_BR) {
         flags &= ~FASTCGI_COMPRESS_GZ;
         if (compress_init(&comp_ctx, COMPRESS_BR) != 0) {
-            print(ERR_STR "Unable to init brotli: %s" CLR_STR, strerror(errno));
+            error("Unable to init brotli");
             flags &= ~FASTCGI_COMPRESS_BR;
         }
     } else if (flags & FASTCGI_COMPRESS_GZ) {
         flags &= ~FASTCGI_COMPRESS_BR;
         if (compress_init(&comp_ctx, COMPRESS_GZ) != 0) {
-            print(ERR_STR "Unable to init gzip: %s" CLR_STR, strerror(errno));
+            error("Unable to init gzip");
             flags &= ~FASTCGI_COMPRESS_GZ;
         }
     }
@@ -434,11 +435,10 @@ int fastcgi_send(fastcgi_conn *conn, sock *client, int flags) {
     while (1) {
         ret = recv(conn->socket, &header, sizeof(header), 0);
         if (ret < 0) {
-            print(ERR_STR "Unable to receive from FastCGI socket: %s" CLR_STR, strerror(errno));
+            error("Unable to receive from FastCGI socket");
             return -1;
         } else if (ret != sizeof(header)) {
-            print(ERR_STR "Unable to receive from FastCGI socket: received len (%li) != header len (%li)" CLR_STR,
-                  ret, sizeof(header));
+            error("Unable to receive from FastCGI socket: received len (%li) != header len (%li)", ret, sizeof(header));
             return -1;
         }
 
@@ -451,7 +451,7 @@ int fastcgi_send(fastcgi_conn *conn, sock *client, int flags) {
         while (rcv_len < content_len + header.paddingLength) {
             ret = recv(conn->socket, content + rcv_len, content_len + header.paddingLength - rcv_len, 0);
             if (ret < 0) {
-                print(ERR_STR "Unable to receive from FastCGI socket: %s" CLR_STR, strerror(errno));
+                error("Unable to receive from FastCGI socket");
                 free(content);
                 return -1;
             }
@@ -463,10 +463,10 @@ int fastcgi_send(fastcgi_conn *conn, sock *client, int flags) {
             int app_status = (body->appStatusB3 << 24) | (body->appStatusB2 << 16) | (body->appStatusB1 << 8) |
                              body->appStatusB0;
             if (body->protocolStatus != FCGI_REQUEST_COMPLETE) {
-                print(ERR_STR "FastCGI protocol error: %i" CLR_STR, body->protocolStatus);
+                error("FastCGI protocol error: %i", body->protocolStatus);
             }
             if (app_status != 0) {
-                print(ERR_STR "FastCGI app terminated with exit code %i" CLR_STR, app_status);
+                error("FastCGI app terminated with exit code %i", app_status);
             }
             close(conn->socket);
             conn->socket = 0;
@@ -513,7 +513,7 @@ int fastcgi_send(fastcgi_conn *conn, sock *client, int flags) {
             } while ((flags & FASTCGI_COMPRESS) && (avail_in != 0 || avail_out != sizeof(comp_out)));
             if (finish_comp) goto finish;
         } else {
-            print(ERR_STR "Unknown FastCGI type: %i" CLR_STR, header.type);
+            error("Unknown FastCGI type: %i", header.type);
         }
         free(content);
     }
@@ -533,11 +533,10 @@ int fastcgi_dump(fastcgi_conn *conn, char *buf, long len) {
     while (1) {
         ret = recv(conn->socket, &header, sizeof(header), 0);
         if (ret < 0) {
-            print(ERR_STR "Unable to receive from FastCGI socket: %s" CLR_STR, strerror(errno));
+            error("Unable to receive from FastCGI socket");
             return -1;
         } else if (ret != sizeof(header)) {
-            print(ERR_STR "Unable to receive from FastCGI socket: received len (%li) != header len (%li)" CLR_STR,
-                  ret, sizeof(header));
+            error("Unable to receive from FastCGI socket: received len (%li) != header len (%li)", ret, sizeof(header));
             return -1;
         }
 
@@ -549,7 +548,7 @@ int fastcgi_dump(fastcgi_conn *conn, char *buf, long len) {
         while (rcv_len < content_len + header.paddingLength) {
             ret = recv(conn->socket, content + rcv_len, content_len + header.paddingLength - rcv_len, 0);
             if (ret < 0) {
-                print(ERR_STR "Unable to receive from FastCGI socket: %s" CLR_STR, strerror(errno));
+                error("Unable to receive from FastCGI socket");
                 free(content);
                 return -1;
             }
@@ -561,10 +560,10 @@ int fastcgi_dump(fastcgi_conn *conn, char *buf, long len) {
             int app_status = (body->appStatusB3 << 24) | (body->appStatusB2 << 16) | (body->appStatusB1 << 8) |
                              body->appStatusB0;
             if (body->protocolStatus != FCGI_REQUEST_COMPLETE) {
-                print(ERR_STR "FastCGI protocol error: %i" CLR_STR, body->protocolStatus);
+                error("FastCGI protocol error: %i", body->protocolStatus);
             }
             if (app_status != 0) {
-                print(ERR_STR "FastCGI app terminated with exit code %i" CLR_STR, app_status);
+                error("FastCGI app terminated with exit code %i", app_status);
             }
             close(conn->socket);
             conn->socket = 0;
@@ -579,7 +578,7 @@ int fastcgi_dump(fastcgi_conn *conn, char *buf, long len) {
         } else if (header.type == FCGI_STDOUT) {
             ptr += snprintf(ptr, len - (ptr - buf), "%.*s", content_len, content);
         } else {
-            print(ERR_STR "Unknown FastCGI type: %i" CLR_STR, header.type);
+            error("Unknown FastCGI type: %i", header.type);
         }
         free(content);
     }
@@ -603,7 +602,7 @@ int fastcgi_receive(fastcgi_conn *conn, sock *client, unsigned long len) {
     while (rcv_len < len) {
         ret = sock_recv(client, buf, sizeof(buf), 0);
         if (ret <= 0) {
-            print(ERR_STR "Unable to receive: %s" CLR_STR, sock_strerror(client));
+            error("Unable to receive: %s", sock_strerror(client));
             return -1;
         }
 
@@ -613,7 +612,7 @@ int fastcgi_receive(fastcgi_conn *conn, sock *client, unsigned long len) {
         if (send(conn->socket, &header, sizeof(header), 0) != sizeof(header)) goto err;
         if (send(conn->socket, buf, ret, 0) != ret) {
             err:
-            print(ERR_STR "Unable to send to FastCGI socket: %s" CLR_STR, strerror(errno));
+            error("Unable to send to FastCGI socket");
             return -2;
         }
     }
diff --git a/src/lib/http.c b/src/lib/http.c
index f894530..ab145f9 100644
--- a/src/lib/http.c
+++ b/src/lib/http.c
@@ -6,6 +6,7 @@
  * @date 2020-12-09
  */
 
+#include "../logger.h"
 #include "http.h"
 #include "utils.h"
 #include "compress.h"
@@ -87,14 +88,14 @@ void http_free_res(http_res *res) {
 
 int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr, int flags) {
     if (hdr->last_field_num > hdr->field_num) {
-        print(ERR_STR "Unable to parse header: Invalid state" CLR_STR);
+        error("Unable to parse header: Invalid state");
         return 3;
     }
 
     char *pos1 = (char *) buf, *pos2 = (char *) end_ptr;
     if (buf[0] == ' ' || buf[0] == '\t') {
         if (hdr->last_field_num == -1) {
-            print(ERR_STR "Unable to parse header" CLR_STR);
+            error("Unable to parse header");
             return 3;
         }
         http_field *f = &hdr->fields[(int) hdr->last_field_num];
@@ -107,7 +108,7 @@ int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr,
 
     pos1 = memchr(buf, ':', end_ptr - buf);
     if (pos1 == NULL) {
-        print(ERR_STR "Unable to parse header" CLR_STR);
+        error("Unable to parse header");
         return 3;
     }
     long len1 = pos1 - buf;
@@ -120,7 +121,7 @@ int http_parse_header_field(http_hdr *hdr, const char *buf, const char *end_ptr,
     int found = http_get_header_field_num_len(hdr, buf, len1);
     if (!(flags & HTTP_MERGE_FIELDS) || found == -1) {
         if (http_add_header_field_len(hdr, buf, len1, pos1, len2 < 0 ? 0 : len2) != 0) {
-            print(ERR_STR "Unable to parse header: Too many header fields" CLR_STR);
+            error("Unable to parse header: Too many header fields");
             return 3;
         }
     } else {
@@ -147,13 +148,13 @@ int http_receive_request(sock *client, http_req *req) {
     while (1) {
         rcv_len = sock_recv(client, buf, CLIENT_MAX_HEADER_SIZE, MSG_PEEK);
         if (rcv_len <= 0) {
-            print("Unable to receive http header: %s", sock_strerror(client));
+            error("Unable to receive http header: %s", sock_strerror(client));
             return -1;
         }
 
         unsigned long header_len = strstr(buf, "\r\n\r\n") - buf + 4;
         if (header_len <= 0) {
-            print(ERR_STR "Unable to parse http header: End of header not found" CLR_STR);
+            error("Unable to parse http header: End of header not found");
             return 5;
         } else {
             rcv_len = sock_recv(client, buf, header_len, 0);
@@ -161,7 +162,7 @@ int http_receive_request(sock *client, http_req *req) {
 
         for (int i = 0; i < header_len; i++) {
             if ((buf[i] >= 0x00 && buf[i] <= 0x1F && buf[i] != '\r' && buf[i] != '\n') || buf[i] == 0x7F) {
-                print(ERR_STR "Unable to parse http header: Header contains illegal characters" CLR_STR);
+                error("Unable to parse http header: Header contains illegal characters");
                 return 4;
             }
         }
@@ -170,7 +171,7 @@ int http_receive_request(sock *client, http_req *req) {
         while (header_len > (ptr - buf + 2)) {
             pos0 = strstr(ptr, "\r\n");
             if (pos0 == NULL) {
-                print(ERR_STR "Unable to parse http header: Invalid header format" CLR_STR);
+                error("Unable to parse http header: Invalid header format");
                 return 1;
             }
 
@@ -179,13 +180,13 @@ int http_receive_request(sock *client, http_req *req) {
                 if (pos1 == NULL) goto err_hdr_fmt;
 
                 if (pos1 - ptr - 1 >= sizeof(req->method)) {
-                    print(ERR_STR "Unable to parse http header: Method name too long" CLR_STR);
+                    error("Unable to parse http header: Method name too long");
                     return 2;
                 }
 
                 for (int i = 0; i < (pos1 - ptr - 1); i++) {
                     if (ptr[i] < 'A' || ptr[i] > 'Z') {
-                        print(ERR_STR "Unable to parse http header: Invalid method" CLR_STR);
+                        error("Unable to parse http header: Invalid method");
                         return 2;
                     }
                 }
@@ -194,12 +195,12 @@ int http_receive_request(sock *client, http_req *req) {
                 pos2 = memchr(pos1, ' ', rcv_len - (pos1 - buf)) + 1;
                 if (pos2 == NULL) {
                     err_hdr_fmt:
-                    print(ERR_STR "Unable to parse http header: Invalid header format" CLR_STR);
+                    error("Unable to parse http header: Invalid header format");
                     return 1;
                 }
 
                 if (memcmp(pos2, "HTTP/", 5) != 0 || memcmp(pos2 + 8, "\r\n", 2) != 0) {
-                    print(ERR_STR "Unable to parse http header: Invalid version" CLR_STR);
+                    error("Unable to parse http header: Invalid version");
                     return 3;
                 }
 
diff --git a/src/lib/rev_proxy.c b/src/lib/rev_proxy.c
index 02de458..57a3a29 100644
--- a/src/lib/rev_proxy.c
+++ b/src/lib/rev_proxy.c
@@ -8,6 +8,7 @@
 
 #include "../defs.h"
 #include "../server.h"
+#include "../logger.h"
 #include "rev_proxy.h"
 #include "utils.h"
 #include "compress.h"
@@ -40,7 +41,7 @@ int rev_proxy_request_header(http_req *req, int enc) {
     } else {
         p_len = snprintf(buf2, sizeof(buf2), "%s, %s", via, buf1);
         if (p_len < 0 || p_len >= sizeof(buf2)) {
-            print(ERR_STR "Header field 'Via' too long" CLR_STR);
+            error("Header field 'Via' too long");
             return -1;
         }
         http_remove_header_field(&req->hdr, "Via", HTTP_REMOVE_ALL);
@@ -57,7 +58,7 @@ int rev_proxy_request_header(http_req *req, int enc) {
                      client_ipv6 ? "\"[" : "", client_addr_str, client_ipv6 ? "]\"" : "",
                      host, enc ? "https" : "http");
     if (p_len < 0 || p_len >= sizeof(buf1)) {
-        print(ERR_STR "Appended part of header field 'Forwarded' too long" CLR_STR);
+        error("Appended part of header field 'Forwarded' too long");
         return -1;
     }
 
@@ -66,7 +67,7 @@ int rev_proxy_request_header(http_req *req, int enc) {
     } else {
         p_len = snprintf(buf2, sizeof(buf2), "%s, %s", forwarded, buf1);
         if (p_len < 0 || p_len >= sizeof(buf2)) {
-            print(ERR_STR "Header field 'Forwarded' too long" CLR_STR);
+            error("Header field 'Forwarded' too long");
             return -1;
         }
         http_remove_header_field(&req->hdr, "Forwarded", HTTP_REMOVE_ALL);
@@ -134,7 +135,7 @@ int rev_proxy_response_header(http_req *req, http_res *res, host_config *conf) {
     const char *via = http_get_header_field(&res->hdr, "Via");
     p_len = snprintf(buf1, sizeof(buf1), "HTTP/%s %s", req->version, SERVER_NAME);
     if (p_len < 0 || p_len >= sizeof(buf1)) {
-        print(ERR_STR "Appended part of header field 'Via' too long" CLR_STR);
+        error("Appended part of header field 'Via' too long");
         return -1;
     }
     if (via == NULL) {
@@ -142,7 +143,7 @@ int rev_proxy_response_header(http_req *req, http_res *res, host_config *conf) {
     } else {
         p_len = snprintf(buf2, sizeof(buf2), "%s, %s", via, buf1);
         if (p_len < 0 || p_len >= sizeof(buf2)) {
-            print(ERR_STR "Header field 'Via' too long" CLR_STR);
+            error("Header field 'Via' too long");
             return -1;
         }
         http_remove_header_field(&res->hdr, "Via", HTTP_REMOVE_ALL);
@@ -190,7 +191,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
 
     retry:
     if (rev_proxy.socket != 0) {
-        print(BLUE_STR "Closing proxy connection" CLR_STR);
+        info(BLUE_STR "Closing proxy connection");
         sock_close(&rev_proxy);
     }
     retry = 0;
@@ -198,7 +199,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
 
     rev_proxy.socket = socket(AF_INET6, SOCK_STREAM, 0);
     if (rev_proxy.socket  < 0) {
-        print(ERR_STR "Unable to create socket: %s" CLR_STR, strerror(errno));
+        error("Unable to create socket");
         res->status = http_get_status(500);
         ctx->origin = INTERNAL;
         return -1;
@@ -217,7 +218,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
         if (host_ent == NULL) {
             res->status = http_get_status(503);
             ctx->origin = SERVER_REQ;
-            print(ERR_STR "Unable to connect to server: Name or service not known" CLR_STR);
+            error("Unable to connect to server: Name or service not known");
             sprintf(err_msg, "Unable to connect to server: Name or service not known.");
             goto proxy_err;
         }
@@ -234,7 +235,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
 
     inet_ntop(address.sin6_family, (void *) &address.sin6_addr, buffer, sizeof(buffer));
 
-    print(BLUE_STR "Connecting to " BLD_STR "[%s]:%i" CLR_STR BLUE_STR "..." CLR_STR, buffer, conf->rev_proxy.port);
+    info(BLUE_STR "Connecting to " BLD_STR "[%s]:%i" CLR_STR BLUE_STR "...", buffer, conf->rev_proxy.port);
     if (connect(rev_proxy.socket, (struct sockaddr *) &address, sizeof(address)) < 0) {
         if (errno == ETIMEDOUT || errno == EINPROGRESS) {
             res->status = http_get_status(504);
@@ -246,7 +247,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
             res->status = http_get_status(500);
             ctx->origin = INTERNAL;
         }
-        print(ERR_STR "Unable to connect to [%s]:%i: %s" CLR_STR, buffer, conf->rev_proxy.port, strerror(errno));
+        error("Unable to connect to [%s]:%i: %s", buffer, conf->rev_proxy.port, strerror(errno));
         sprintf(err_msg, "Unable to connect to server: %s.", strerror(errno));
         goto proxy_err;
     }
@@ -259,7 +260,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
         rev_proxy_timeout_err:
         res->status = http_get_status(500);
         ctx->origin = INTERNAL;
-        print(ERR_STR "Unable to set timeout for reverse proxy socket: %s" CLR_STR, strerror(errno));
+        error("Unable to set timeout for reverse proxy socket");
         sprintf(err_msg, "Unable to set timeout for reverse proxy socket: %s", strerror(errno));
         goto proxy_err;
     }
@@ -277,14 +278,14 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
         if (ret < 0) {
             res->status = http_get_status(502);
             ctx->origin = SERVER_REQ;
-            print(ERR_STR "Unable to perform handshake: %s" CLR_STR, sock_strerror(&rev_proxy));
+            error("Unable to perform handshake: %s", sock_strerror(&rev_proxy));
             sprintf(err_msg, "Unable to perform handshake: %s.", sock_strerror(&rev_proxy));
             goto proxy_err;
         }
     }
 
     rev_proxy_host = conf->name;
-    print(BLUE_STR "Established new connection with " BLD_STR "[%s]:%i" CLR_STR, buffer, conf->rev_proxy.port);
+    info(BLUE_STR "Established new connection with " BLD_STR "[%s]:%i", buffer, conf->rev_proxy.port);
 
     rev_proxy:
     connection = http_get_header_field(&req->hdr, "Connection");
@@ -314,7 +315,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
     if (ret < 0) {
         res->status = http_get_status(502);
         ctx->origin = SERVER_REQ;
-        print(ERR_STR "Unable to send request to server (1): %s" CLR_STR, sock_strerror(&rev_proxy));
+        error("Unable to send request to server (1): %s", sock_strerror(&rev_proxy));
         sprintf(err_msg, "Unable to send request to server: %s.", sock_strerror(&rev_proxy));
         retry = tries < 4;
         goto proxy_err;
@@ -335,20 +336,20 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
         if (ret == -1) {
             res->status = http_get_status(502);
             ctx->origin = SERVER_REQ;
-            print(ERR_STR "Unable to send request to server (2): %s" CLR_STR, sock_strerror(&rev_proxy));
+            error("Unable to send request to server (2): %s", sock_strerror(&rev_proxy));
             sprintf(err_msg, "Unable to send request to server: %s.", sock_strerror(&rev_proxy));
             retry = tries < 4;
             goto proxy_err;
         } else if (ret == -2) {
             res->status = http_get_status(400);
             ctx->origin = CLIENT_REQ;
-            print(ERR_STR "Unable to receive request from client: %s" CLR_STR, sock_strerror(client));
+            error("Unable to receive request from client: %s", sock_strerror(client));
             sprintf(err_msg, "Unable to receive request from client: %s.", sock_strerror(client));
             return -1;
         }
         res->status = http_get_status(500);
         ctx->origin = INTERNAL;
-        print(ERR_STR "Unknown Error" CLR_STR);
+        error("Unknown Error");
         return -1;
     }
 
@@ -364,7 +365,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
             res->status = http_get_status(502);
             ctx->origin = SERVER_RES;
         }
-        print(ERR_STR "Unable to receive response from server: %s" CLR_STR, sock_strerror(&rev_proxy));
+        error("Unable to receive response from server: %s", sock_strerror(&rev_proxy));
         sprintf(err_msg, "Unable to receive response from server: %s.", sock_strerror(&rev_proxy));
         retry = tries < 4;
         goto proxy_err;
@@ -376,7 +377,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
     if (header_len <= 0) {
         res->status = http_get_status(502);
         ctx->origin = SERVER_RES;
-        print(ERR_STR "Unable to parse header: End of header not found" CLR_STR);
+        error("Unable to parse header: End of header not found");
         sprintf(err_msg, "Unable to parser header: End of header not found.");
         goto proxy_err;
     }
@@ -385,7 +386,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
         if ((buf[i] >= 0x00 && buf[i] <= 0x1F && buf[i] != '\r' && buf[i] != '\n') || buf[i] == 0x7F) {
             res->status = http_get_status(502);
             ctx->origin = SERVER_RES;
-            print(ERR_STR "Unable to parse header: Header contains illegal characters" CLR_STR);
+            error("Unable to parse header: Header contains illegal characters");
             sprintf(err_msg, "Unable to parse header: Header contains illegal characters.");
             goto proxy_err;
         }
@@ -397,7 +398,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
         if (pos0 == NULL) {
             res->status = http_get_status(502);
             ctx->origin = SERVER_RES;
-            print(ERR_STR "Unable to parse header: Invalid header format" CLR_STR);
+            error("Unable to parse header: Invalid header format");
             sprintf(err_msg, "Unable to parse header: Invalid header format.");
             goto proxy_err;
         }
@@ -405,7 +406,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
             if (strncmp(ptr, "HTTP/", 5) != 0) {
                 res->status = http_get_status(502);
                 ctx->origin = SERVER_RES;
-                print(ERR_STR "Unable to parse header: Invalid header format" CLR_STR);
+                error("Unable to parse header: Invalid header format");
                 sprintf(err_msg, "Unable to parse header: Invalid header format.");
                 goto proxy_err;
             }
@@ -420,7 +421,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
             } else if (res->status == NULL) {
                 res->status = http_get_status(502);
                 ctx->origin = SERVER_RES;
-                print(ERR_STR "Unable to parse header: Invalid or unknown status code" CLR_STR);
+                error("Unable to parse header: Invalid or unknown status code");
                 sprintf(err_msg, "Unable to parse header: Invalid or unknown status code.");
                 goto proxy_err;
             }
@@ -429,7 +430,7 @@ int rev_proxy_init(http_req *req, http_res *res, http_status_ctx *ctx, host_conf
             if (ret != 0) {
                 res->status = http_get_status(502);
                 ctx->origin = SERVER_RES;
-                print(ERR_STR "Unable to parse header" CLR_STR);
+                error("Unable to parse header");
                 sprintf(err_msg, "Unable to parse header.");
                 goto proxy_err;
             }
@@ -464,13 +465,13 @@ int rev_proxy_send(sock *client, unsigned long len_to_send, int flags) {
     if (flags & REV_PROXY_COMPRESS_BR) {
         flags &= ~REV_PROXY_COMPRESS_GZ;
         if (compress_init(&comp_ctx, COMPRESS_BR) != 0) {
-            print(ERR_STR "Unable to init brotli: %s" CLR_STR, strerror(errno));
+            error("Unable to init brotli");
             flags &= ~REV_PROXY_COMPRESS_BR;
         }
     } else if (flags & REV_PROXY_COMPRESS_GZ) {
         flags &= ~REV_PROXY_COMPRESS_BR;
         if (compress_init(&comp_ctx, COMPRESS_GZ) != 0) {
-            print(ERR_STR "Unable to init gzip: %s" CLR_STR, strerror(errno));
+            error("Unable to init gzip");
             flags &= ~REV_PROXY_COMPRESS_GZ;
         }
     }
@@ -481,9 +482,9 @@ int rev_proxy_send(sock *client, unsigned long len_to_send, int flags) {
             ret = sock_get_chunk_header(&rev_proxy);
             if (ret < 0) {
                 if (ret == -1) {
-                    print("Unable to receive from server: Malformed chunk header");
+                    error("Unable to receive from server: Malformed chunk header");
                 } else {
-                    print("Unable to receive from server: %s", sock_strerror(&rev_proxy));
+                    error("Unable to receive from server: %s", sock_strerror(&rev_proxy));
                 }
                 break;
             }
@@ -503,7 +504,7 @@ int rev_proxy_send(sock *client, unsigned long len_to_send, int flags) {
             unsigned long avail_in, avail_out;
             ret = sock_recv(&rev_proxy, buffer, CHUNK_SIZE < (len_to_send - snd_len) ? CHUNK_SIZE : len_to_send - snd_len, 0);
             if (ret <= 0) {
-                print("Unable to receive from server: %s", sock_strerror(&rev_proxy));
+                error("Unable to receive from server: %s", sock_strerror(&rev_proxy));
                 break;
             }
             len = ret;
@@ -534,7 +535,7 @@ int rev_proxy_send(sock *client, unsigned long len_to_send, int flags) {
                     if (flags & REV_PROXY_CHUNKED) ret = sock_send(client, "\r\n", 2, 0);
                     if (ret <= 0) {
                         err:
-                        print(ERR_STR "Unable to send: %s" CLR_STR, sock_strerror(client));
+                        error("Unable to send: %s", sock_strerror(client));
                         break;
                     }
                 }
@@ -551,7 +552,7 @@ int rev_proxy_send(sock *client, unsigned long len_to_send, int flags) {
     if (flags & REV_PROXY_CHUNKED) {
         ret = sock_send(client, "0\r\n\r\n", 5, 0);
         if (ret <= 0) {
-            print(ERR_STR "Unable to send: %s" CLR_STR, sock_strerror(client));
+            error("Unable to send: %s", sock_strerror(client));
             return -1;
         }
     }
diff --git a/src/lib/sock.c b/src/lib/sock.c
index 63e3b56..4cfff6c 100644
--- a/src/lib/sock.c
+++ b/src/lib/sock.c
@@ -188,7 +188,6 @@ long sock_get_chunk_header(sock *s) {
     char buf[16];
 
     do {
-        print("debug1");  // TODO remove
         ret = sock_recv(s, buf, sizeof(buf), MSG_PEEK);
         if (ret <= 0) return -2;
         else if (ret < 2) continue;
diff --git a/src/lib/utils.c b/src/lib/utils.c
index 9f89a49..63e0d5c 100644
--- a/src/lib/utils.c
+++ b/src/lib/utils.c
@@ -13,8 +13,6 @@
 #include <stdlib.h>
 
 
-char *log_prefix;
-
 static const char base64_encode_table[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 static const int base64_mod_table[3] = {0, 2, 1};
 
diff --git a/src/lib/utils.h b/src/lib/utils.h
index ea2bb03..608a60a 100644
--- a/src/lib/utils.h
+++ b/src/lib/utils.h
@@ -19,19 +19,6 @@
 #define HTTP_STR "\x1B[1;31m"
 #define HTTPS_STR "\x1B[1;32m"
 
-extern char *log_prefix;
-
-
-#define out_1(fmt) fprintf(stdout, "%s" fmt "\n", log_prefix)
-#define out_2(fmt, args...) fprintf(stdout, "%s" fmt "\n", log_prefix, args)
-
-#define out_x(x, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, FUNC, ...) FUNC
-
-#define print(...) out_x(, ##__VA_ARGS__, out_2(__VA_ARGS__), out_2(__VA_ARGS__), out_2(__VA_ARGS__), \
-                         out_2(__VA_ARGS__), out_2(__VA_ARGS__), out_2(__VA_ARGS__), out_2(__VA_ARGS__), \
-                         out_2(__VA_ARGS__), out_1(__VA_ARGS__))
-
-
 char *format_duration(unsigned long micros, char *buf);
 
 int url_encode_component(const void *in, size_t size_in, char *out, size_t size_out);
diff --git a/src/lib/websocket.c b/src/lib/websocket.c
index c32a1b7..bbb4e46 100644
--- a/src/lib/websocket.c
+++ b/src/lib/websocket.c
@@ -7,6 +7,7 @@
  */
 
 #include "../defs.h"
+#include "../logger.h"
 #include "websocket.h"
 #include "utils.h"
 
@@ -45,10 +46,10 @@ int ws_recv_frame_header(sock *s, ws_frame *frame) {
 
     long ret = sock_recv(s, buf, 2, 0);
     if (ret < 0) {
-        print(ERR_STR "Unable to receive from socket: %s" CLR_STR, strerror(errno));
+        error("Unable to receive from socket");
         return -1;
     } else if (ret != 2) {
-        print(ERR_STR "Unable to receive 2 bytes from socket" CLR_STR);
+        error("Unable to receive 2 bytes from socket");
         return -2;
     }
 
@@ -70,10 +71,10 @@ int ws_recv_frame_header(sock *s, ws_frame *frame) {
 
     ret = sock_recv(s, buf, remaining, 0);
     if (ret < 0) {
-        print(ERR_STR "Unable to receive from socket: %s" CLR_STR, strerror(errno));
+        error("Unable to receive from socket");
         return -1;
     } else if (ret != remaining) {
-        print(ERR_STR "Unable to receive correct number of bytes from socket" CLR_STR);
+        error("Unable to receive correct number of bytes from socket");
         return -2;
     }
 
@@ -134,10 +135,10 @@ int ws_send_frame_header(sock *s, ws_frame *frame) {
 
     long ret = sock_send(s, buf, ptr - buf, frame->len != 0 ? MSG_MORE : 0);
     if (ret < 0) {
-        print(ERR_STR "Unable to send to socket: %s" CLR_STR, strerror(errno));
+        error("Unable to send to socket");
         return -1;
     } else if (ret != ptr - buf) {
-        print(ERR_STR "Unable to send to socket" CLR_STR);
+        error("Unable to send to socket");
         return -2;
     }
 
@@ -161,13 +162,13 @@ int ws_handle_connection(sock *s1, sock *s2) {
         if (terminate) {
             break;
         } else if (ret < 0) {
-            print(ERR_STR "Unable to poll sockets: %s" CLR_STR, strerror(errno));
+            error("Unable to poll sockets");
             return -1;
         } else if (n_readable == 0) {
-            print(ERR_STR "Connection timed out" CLR_STR);
+            error("Connection timed out");
             return -2;
         } else if (n_error > 0) {
-            print(ERR_STR "Peer closed connection" CLR_STR);
+            error("Peer closed connection");
             return -3;
         }
 
@@ -176,7 +177,7 @@ int ws_handle_connection(sock *s1, sock *s2) {
             sock *o = (s == s1) ? s2 : s1;
             if (ws_recv_frame_header(s, &frame) != 0) return -3;
 
-            // print("WebSocket: Peer %s, Opcode=0x%X, Len=%li", (s == s1) ? "1" : "2", frame.opcode, frame.len);
+            // debug("WebSocket: Peer %s, Opcode=0x%X, Len=%li", (s == s1) ? "1" : "2", frame.opcode, frame.len);
 
             if (frame.opcode == 0x8) {
                 n_sock--;
@@ -193,10 +194,10 @@ int ws_handle_connection(sock *s1, sock *s2) {
             if (frame.len > 0) {
                 ret = sock_splice(o, s, buf, sizeof(buf), frame.len);
                 if (ret < 0) {
-                    print(ERR_STR "Unable to forward data in WebSocket: %s" CLR_STR, strerror(errno));
+                    error("Unable to forward data in WebSocket");
                     return -4;
                 } else if (ret != frame.len) {
-                    print(ERR_STR "Unable to forward correct number of bytes in WebSocket" CLR_STR);
+                    error("Unable to forward correct number of bytes in WebSocket");
                     return -4;
                 }
             }
diff --git a/src/logger.c b/src/logger.c
new file mode 100644
index 0000000..c43e87a
--- /dev/null
+++ b/src/logger.c
@@ -0,0 +1,257 @@
+/**
+ * sesimos - secure, simple, modern web server
+ * @brief Logger
+ * @file src/logger.h
+ * @author Lorenz Stechauner
+ * @date 2022-12-10
+ */
+
+#include "logger.h"
+#include "lib/utils.h"
+
+#include <stdio.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <errno.h>
+#include <string.h>
+#include <stdarg.h>
+#include <signal.h>
+#include <malloc.h>
+
+#define LOG_MAX_MSG_SIZE 2048
+#define LOG_BUF_SIZE 16
+#define LOG_NAME_LEN 8
+#define LOG_PREFIX_LEN 256
+
+typedef struct {
+    log_lvl_t lvl;
+    char name[LOG_NAME_LEN];
+    char prefix[LOG_PREFIX_LEN];
+    char txt[LOG_MAX_MSG_SIZE];
+} log_msg_t;
+
+typedef struct {
+    int rd;
+    int wr;
+    log_msg_t msgs[LOG_BUF_SIZE];
+} buf_t;
+
+static volatile sig_atomic_t logger_alive = 0;
+static sem_t sem_buf, sem_buf_free, sem_buf_used;
+static buf_t buffer;
+
+static pthread_key_t key_name = -1, key_prefix = -1;
+static char global_name[LOG_NAME_LEN] = "", global_prefix[LOG_PREFIX_LEN] = "";
+
+static const char *level_keywords[] = {
+        "EMERG",
+        "ALERT",
+        "CRIT",
+        "ERROR",
+        "WARN",
+        "NOTICE",
+        "INFO",
+        "DEBUG"
+};
+
+void logmsgf(log_lvl_t level, const char *restrict format, ...) {
+    char buf[256];
+    char err_buf[64];
+    va_list args;
+    va_start(args, format);
+
+    const char *color = (level <= LOG_ERROR) ? ERR_STR : ((level <= LOG_WARNING) ? WRN_STR : "");
+    if (errno != 0) {
+        strerror_r(errno, err_buf, sizeof(err_buf));
+        snprintf(buf, sizeof(buf), "%s%s: %s" CLR_STR, color, format, err_buf);
+    } else {
+        snprintf(buf, sizeof(buf), "%s%s" CLR_STR, color, format);
+    }
+
+    void *name = pthread_getspecific(key_name);
+    if (name == NULL && global_name[0] != 0) name = global_name;
+    void *prefix = pthread_getspecific(key_prefix);
+    if (prefix == NULL && global_prefix[0] != 0) prefix = global_prefix;
+
+    if (!logger_alive) {
+        // no logger thread running
+        // simply write to stdout/stderr without synchronization
+        FILE *out = (level <= LOG_CRITICAL) ? stderr : stdout;
+        fprintf(out, "%s[%-6s][%-6s]%s%s ", color, level_keywords[level], (name != NULL) ? (char *) name : "", CLR_STR, (prefix != NULL) ? (char *) prefix : "");
+        vfprintf(out, buf, args);
+        fprintf(out, "\n");
+    } else {
+        // wait for free slot in buffer
+        try_again_free:
+        if (sem_wait(&sem_buf_free) != 0) {
+            if (errno == EINTR) {
+                goto try_again_free;
+            } else {
+                strerror_r(errno, err_buf, sizeof(err_buf));
+                fprintf(stderr, "[logger] " ERR_STR "Unable to lock semaphore: %s" CLR_STR "\n", err_buf);
+            }
+            // cleanup
+            va_end(args);
+            return;
+        }
+
+        // try to lock buffer
+        try_again_buf:
+        if (sem_wait(&sem_buf) != 0) {
+            if (errno == EINTR) {
+                goto try_again_buf;
+            } else {
+                strerror_r(errno, err_buf, sizeof(err_buf));
+                fprintf(stderr, "[logger] " ERR_STR "Unable to lock semaphore: %s" CLR_STR "\n", err_buf);
+            }
+            // cleanup
+            sem_post(&sem_buf_free);
+            va_end(args);
+            return;
+        }
+
+        // write message to buffer
+        log_msg_t *msg = &buffer.msgs[buffer.rd];
+        buffer.rd = (buffer.rd + 1) % LOG_BUF_SIZE;
+
+        vsnprintf(msg->txt, sizeof(msg->txt), buf, args);
+        msg->lvl = level;
+
+        if (name != NULL) {
+            snprintf(msg->name, sizeof(msg->name), "%s", (char *) name);
+        } else {
+            msg->name[0] = 0;
+        }
+
+        if (prefix != NULL) {
+            snprintf(msg->prefix, sizeof(msg->prefix), "%s", (char *) prefix);
+        } else {
+            msg->prefix[0] = 0;
+        }
+
+        // unlock buffer
+        sem_post(&sem_buf);
+
+        // unlock slot in buffer for logger
+        sem_post(&sem_buf_used);
+    }
+
+    // cleanup
+    va_end(args);
+}
+
+static void logger_destroy(void) {
+    sem_destroy(&sem_buf);
+    sem_destroy(&sem_buf_free);
+    sem_destroy(&sem_buf_used);
+}
+
+static int logger_init(void) {
+    char err_buf[64];
+    int ret;
+
+    // try to initialize all three semaphores
+    if (sem_init(&sem_buf, 0, 1) != 0 || sem_init(&sem_buf_free, 0, 1) != 0 || sem_init(&sem_buf_used, 0, 0) != 0) {
+        strerror_r(errno, err_buf, sizeof(err_buf));
+        fprintf(stderr, "[logger] " ERR_STR "Unable to initialize semaphore: %s" CLR_STR "\n", err_buf);
+        logger_destroy();
+        return -1;
+    }
+
+    // initialize read/write heads
+    buffer.rd = 0;
+    buffer.wr = 0;
+
+    // initialize thread specific values (keys)
+    if ((ret = pthread_key_create(&key_name, free)) != 0 || (ret = pthread_key_create(&key_prefix, free)) != 0) {
+        strerror_r(ret, err_buf, sizeof(err_buf));
+        fprintf(stderr, "[logger] " ERR_STR "Unable to initialize thread specific values: %s" CLR_STR "\n", err_buf);
+        logger_destroy();
+        return -1;
+    }
+
+    return 0;
+}
+
+static int logger_remaining(void) {
+    int val = 0;
+    sem_getvalue(&sem_buf_used, &val);
+    return val;
+}
+
+void logger_set_name(const char *restrict name) {
+    if (key_name == -1) {
+        // not initialized
+        strncpy(global_name, name, sizeof(global_name));
+    } else {
+        char err_buf[64];
+        int ret;
+        void *ptr = pthread_getspecific(key_name);
+        if (!ptr) {
+            ptr = malloc(LOG_NAME_LEN);
+            if ((ret = pthread_setspecific(key_name, ptr)) != 0) {
+                strerror_r(ret, err_buf, sizeof(err_buf));
+                fprintf(stderr, "[logger] " ERR_STR "Unable to set thread specific values: %s" CLR_STR "\n", err_buf);
+                return;
+            }
+        }
+        strncpy(ptr, name, LOG_NAME_LEN);
+    }
+}
+
+void logger_set_prefix(const char *restrict prefix) {
+    if (key_name == -1) {
+        strncpy(global_prefix, prefix, sizeof(global_prefix));
+    } else {
+        char err_buf[64];
+        int ret;
+        void *ptr = pthread_getspecific(key_name);
+        if (!ptr) {
+            ptr = malloc(LOG_PREFIX_LEN);
+            pthread_setspecific(key_prefix, ptr);
+            if ((ret = pthread_setspecific(key_prefix, ptr)) != 0) {
+                strerror_r(ret, err_buf, sizeof(err_buf));
+                fprintf(stderr, "[logger] " ERR_STR "Unable to set thread specific values: %s" CLR_STR "\n", err_buf);
+                return;
+            }
+        }
+        strncpy(ptr, prefix, LOG_PREFIX_LEN);
+    }
+}
+
+void logger_stop(void) {
+    logger_alive = 0;
+}
+
+void logger(void) {
+    char err_buf[64];
+
+    if (logger_init() != 0)
+        return;
+
+    logger_set_name("logger");
+    logger_alive = 1;
+
+    while (logger_alive || logger_remaining() > 0) {
+        // wait for buffer to be filled
+        if (sem_wait(&sem_buf_used) != 0) {
+            if (errno == EINTR) {
+                continue;
+            } else {
+                strerror_r(errno, err_buf, sizeof(err_buf));
+                fprintf(stderr, "[logger] " ERR_STR "Unable to lock semaphore: %s" CLR_STR "\n", err_buf);
+                break;
+            }
+        }
+
+        log_msg_t *msg = &buffer.msgs[buffer.wr];
+        buffer.wr = (buffer.wr + 1) % LOG_BUF_SIZE;
+
+        fprintf((msg->lvl <= LOG_CRITICAL) ? stderr : stdout, "[%s]%s %s\n", msg->name, (msg->prefix[0] != 0) ? msg->prefix : "", msg->txt);
+
+        // unlock slot in buffer
+        sem_post(&sem_buf_free);
+    }
+
+    logger_destroy();
+}
diff --git a/src/logger.h b/src/logger.h
new file mode 100644
index 0000000..957bb61
--- /dev/null
+++ b/src/logger.h
@@ -0,0 +1,40 @@
+/**
+ * sesimos - secure, simple, modern web server
+ * @brief Logger (header file)
+ * @file src/logger.h
+ * @author Lorenz Stechauner
+ * @date 2022-12-10
+ */
+
+#ifndef SESIMOS_LOGGER_H
+#define SESIMOS_LOGGER_H
+
+#define LOG_DEBUG 7
+#define LOG_INFO 6
+#define LOG_NOTICE 5
+#define LOG_WARNING 4
+#define LOG_ERROR 3
+#define LOG_CRITICAL 2
+#define LOG_ALERT 1
+
+typedef unsigned char log_lvl_t;
+
+#define debug(...) logmsgf(LOG_DEBUG, __VA_ARGS__)
+#define info(...) logmsgf(LOG_INFO, __VA_ARGS__)
+#define notice(...) logmsgf(LOG_NOTICE, __VA_ARGS__)
+#define warning(...) logmsgf(LOG_WARNING, __VA_ARGS__)
+#define error(...) logmsgf(LOG_ERROR, __VA_ARGS__)
+#define critical(...) logmsgf(LOG_CRITICAL, __VA_ARGS__)
+#define alert(...) logmsgf(LOG_ALERT, __VA_ARGS__)
+
+void logmsgf(log_lvl_t level, const char *restrict format, ...);
+
+void logger_set_name(const char *restrict name);
+
+void logger_set_prefix(const char *restrict prefix);
+
+void logger(void);
+
+void logger_stop(void);
+
+#endif //SESIMOS_LOGGER_H
diff --git a/src/server.c b/src/server.c
index 4dc2790..284924a 100644
--- a/src/server.c
+++ b/src/server.c
@@ -9,6 +9,7 @@
 #include "defs.h"
 #include "server.h"
 #include "client.h"
+#include "logger.h"
 
 #include "lib/cache.h"
 #include "lib/config.h"
@@ -58,7 +59,7 @@ static int ssl_servername_cb(SSL *ssl, int *ad, void *arg) {
 }
 
 void destroy(int _) {
-    fprintf(stderr, "\n" ERR_STR "Terminating forcefully!" CLR_STR "\n");
+    error("Terminating forcefully!");
     int status = 0;
     int ret;
     int kills = 0;
@@ -66,11 +67,11 @@ void destroy(int _) {
         if (children[i] != 0) {
             ret = waitpid(children[i], &status, WNOHANG);
             if (ret < 0) {
-                fprintf(stderr, ERR_STR "Unable to wait for child process (PID %i): %s" CLR_STR "\n", children[i], strerror(errno));
+                critical("Unable to wait for child process (PID %i)", children[i]);
             } else if (ret == children[i]) {
                 children[i] = 0;
                 if (status != 0) {
-                    fprintf(stderr, ERR_STR "Child process with PID %i terminated with exit code %i" CLR_STR "\n", ret, status);
+                    critical("Child process with PID %i terminated with exit code %i", ret, status);
                 }
             } else {
                 kill(children[i], SIGKILL);
@@ -79,7 +80,7 @@ void destroy(int _) {
         }
     }
     if (kills > 0) {
-        fprintf(stderr, ERR_STR "Killed %i child process(es)" CLR_STR "\n", kills);
+        critical("Killed %i child process(es)", kills);
     }
     cache_unload();
     config_unload();
@@ -87,7 +88,7 @@ void destroy(int _) {
 }
 
 void terminate(int _) {
-    fprintf(stderr, "\nTerminating gracefully...\n");
+    notice("Terminating gracefully...");
     active = 0;
 
     signal(SIGINT, destroy);
@@ -105,11 +106,11 @@ void terminate(int _) {
         if (children[i] != 0) {
             ret = waitpid(children[i], &status, WNOHANG);
             if (ret < 0) {
-                fprintf(stderr, ERR_STR "Unable to wait for child process (PID %i): %s" CLR_STR "\n", children[i], strerror(errno));
+                critical("Unable to wait for child process (PID %i)", children[i]);
             } else if (ret == children[i]) {
                 children[i] = 0;
                 if (status != 0) {
-                    fprintf(stderr, ERR_STR "Child process with PID %i terminated with exit code %i" CLR_STR "\n", ret, status);
+                    critical("Child process with PID %i terminated with exit code %i", ret, status);
                 }
             } else {
                 kill(children[i], SIGTERM);
@@ -119,18 +120,18 @@ void terminate(int _) {
     }
 
     if (wait_num > 0) {
-        fprintf(stderr, "Waiting for %i child process(es)...\n", wait_num);
+        info("Waiting for %i child process(es)...", wait_num);
     }
 
     for (int i = 0; i < MAX_CHILDREN; i++) {
         if (children[i] != 0) {
             ret = waitpid(children[i], &status, 0);
             if (ret < 0) {
-                fprintf(stderr, ERR_STR "Unable to wait for child process (PID %i): %s" CLR_STR "\n", children[i], strerror(errno));
+                critical("Unable to wait for child process (PID %i)", children[i]);
             } else if (ret == children[i]) {
                 children[i] = 0;
                 if (status != 0) {
-                    fprintf(stderr, ERR_STR "Child process with PID %i terminated with exit code %i" CLR_STR "\n", ret, status);
+                    critical("Child process with PID %i terminated with exit code %i", ret, status);
                 }
             }
         }
@@ -142,10 +143,9 @@ void terminate(int _) {
         signal(SIGTERM, SIG_IGN);
         struct timespec ts = {.tv_sec = 0, .tv_nsec = 50000000};
         nanosleep(&ts, &ts);
-        fprintf(stderr, "\nGoodbye\n");
-    } else {
-        fprintf(stderr, "Goodbye\n");
     }
+
+    info("Goodbye");
     cache_unload();
     config_unload();
     exit(0);
@@ -173,8 +173,10 @@ int main(int argc, const char *argv[]) {
             {.sin6_family = AF_INET6, .sin6_addr = IN6ADDR_ANY_INIT, .sin6_port = htons(443)}
     };
 
+    logger_set_name("server");
+
     if (setvbuf(stdout, NULL, _IOLBF, 0) != 0) {
-        fprintf(stderr, ERR_STR "Unable to set stdout to line-buffered mode: %s" CLR_STR, strerror(errno));
+        critical("Unable to set stdout to line-buffered mode");
         return 1;
     }
     printf("Sesimos web server " SERVER_VERSION "\n");
@@ -197,13 +199,13 @@ int main(int argc, const char *argv[]) {
             return 0;
         } else if (strcmp(arg, "-c") == 0 || strcmp(arg, "--config") == 0) {
             if (i == argc - 1) {
-                fprintf(stderr, ERR_STR "Unable to parse argument %s, usage: --config <CONFIG-FILE>" CLR_STR "\n", arg);
+                critical("Unable to parse argument %s, usage: --config <CONFIG-FILE>", arg);
                 config_unload();
                 return 1;
             }
             config_file = argv[++i];
         } else {
-            fprintf(stderr, ERR_STR "Unable to parse argument '%s'" CLR_STR "\n", arg);
+            critical("Unable to parse argument '%s'", arg);
             config_unload();
             return 1;
         }
@@ -220,14 +222,14 @@ int main(int argc, const char *argv[]) {
     sockets[1] = socket(AF_INET6, SOCK_STREAM, 0);
     if (sockets[1] < 0) {
         socket_err:
-        fprintf(stderr, ERR_STR "Unable to create socket: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to create socket");
         config_unload();
         return 1;
     }
 
     for (int i = 0; i < NUM_SOCKETS; i++) {
         if (setsockopt(sockets[i], SOL_SOCKET, SO_REUSEADDR, &YES, sizeof(YES)) < 0) {
-            fprintf(stderr, ERR_STR "Unable to set options for socket %i: %s" CLR_STR "\n", i, strerror(errno));
+            critical("Unable to set options for socket %i", i);
             config_unload();
             return 1;
         }
@@ -236,7 +238,7 @@ int main(int argc, const char *argv[]) {
     if (bind(sockets[0], (struct sockaddr *) &addresses[0], sizeof(addresses[0])) < 0) goto bind_err;
     if (bind(sockets[1], (struct sockaddr *) &addresses[1], sizeof(addresses[1])) < 0) {
         bind_err:
-        fprintf(stderr, ERR_STR "Unable to bind socket to address: %s" CLR_STR "\n", strerror(errno));
+        critical("Unable to bind socket to address");
         config_unload();
         return 1;
     }
@@ -247,7 +249,7 @@ int main(int argc, const char *argv[]) {
     if (geoip_dir[0] != 0) {
         DIR *geoip = opendir(geoip_dir);
         if (geoip == NULL) {
-            fprintf(stderr, ERR_STR "Unable to open GeoIP dir: %s" CLR_STR "\n", strerror(errno));
+            critical("Unable to open GeoIP dir");
             config_unload();
             return 1;
         }
@@ -256,21 +258,21 @@ int main(int argc, const char *argv[]) {
         while ((dir = readdir(geoip)) != NULL) {
             if (strcmp(dir->d_name + strlen(dir->d_name) - 5, ".mmdb") != 0) continue;
             if (i >= MAX_MMDB) {
-                fprintf(stderr, ERR_STR "Too many .mmdb files" CLR_STR "\n");
+                critical("Too many .mmdb files");
                 config_unload();
                 return 1;
             }
             sprintf(buf, "%s/%s", geoip_dir, dir->d_name);
             ret = MMDB_open(buf, 0, &mmdbs[i]);
             if (ret != MMDB_SUCCESS) {
-                fprintf(stderr, ERR_STR "Unable to open .mmdb file: %s" CLR_STR "\n", MMDB_strerror(ret));
+                critical("Unable to open .mmdb file: %s", MMDB_strerror(ret));
                 config_unload();
                 return 1;
             }
             i++;
         }
         if (i == 0) {
-            fprintf(stderr, ERR_STR "No .mmdb files found in %s" CLR_STR "\n", geoip_dir);
+            critical("No .mmdb files found in %s", geoip_dir);
             config_unload();
             return 1;
         }
@@ -304,13 +306,13 @@ int main(int argc, const char *argv[]) {
         SSL_CTX_set_tlsext_servername_callback(ctx, ssl_servername_cb);
 
         if (SSL_CTX_use_certificate_chain_file(ctx, conf->full_chain) != 1) {
-            fprintf(stderr, ERR_STR "Unable to load certificate chain file: %s: %s" CLR_STR "\n", ERR_reason_error_string(ERR_get_error()), conf->full_chain);
+            critical("Unable to load certificate chain file: %s: %s", ERR_reason_error_string(ERR_get_error()), conf->full_chain);
             config_unload();
             cache_unload();
             return 1;
         }
         if (SSL_CTX_use_PrivateKey_file(ctx, conf->priv_key, SSL_FILETYPE_PEM) != 1) {
-            fprintf(stderr, ERR_STR "Unable to load private key file: %s: %s" CLR_STR "\n", ERR_reason_error_string(ERR_get_error()), conf->priv_key);
+            critical("Unable to load private key file: %s: %s", ERR_reason_error_string(ERR_get_error()), conf->priv_key);
             config_unload();
             cache_unload();
             return 1;
@@ -324,7 +326,7 @@ int main(int argc, const char *argv[]) {
 
     for (int i = 0; i < NUM_SOCKETS; i++) {
         if (listen(sockets[i], LISTEN_BACKLOG) < 0) {
-            fprintf(stderr, ERR_STR "Unable to listen on socket %i: %s" CLR_STR "\n", i, strerror(errno));
+            critical("Unable to listen on socket %i", i);
             config_unload();
             cache_unload();
             return 1;
@@ -336,12 +338,13 @@ int main(int argc, const char *argv[]) {
         poll_fds[i].events = POLLIN;
     }
 
-    fprintf(stderr, "Ready to accept connections\n");
+    errno = 0;
+    info("Ready to accept connections");
 
     while (active) {
         ready_sockets_num = poll(poll_fds, NUM_SOCKETS, 1000);
         if (ready_sockets_num < 0) {
-            fprintf(stderr, ERR_STR "Unable to poll sockets: %s" CLR_STR "\n", strerror(errno));
+            critical("Unable to poll sockets");
             terminate(0);
             return 1;
         }
@@ -350,7 +353,7 @@ int main(int argc, const char *argv[]) {
             if (poll_fds[i].revents & POLLIN) {
                 client_fd = accept(sockets[i], (struct sockaddr *) &client_addr, &client_addr_len);
                 if (client_fd < 0) {
-                    fprintf(stderr, ERR_STR "Unable to accept connection: %s" CLR_STR "\n", strerror(errno));
+                    critical("Unable to accept connection");
                     continue;
                 }
 
@@ -374,7 +377,7 @@ int main(int argc, const char *argv[]) {
                         }
                     }
                 } else {
-                    fprintf(stderr, ERR_STR "Unable to create child process: %s" CLR_STR "\n", strerror(errno));
+                    critical("Unable to create child process");
                 }
             }
         }
@@ -385,11 +388,11 @@ int main(int argc, const char *argv[]) {
             if (children[i] != 0) {
                 ret = waitpid(children[i], &status, WNOHANG);
                 if (ret < 0) {
-                    fprintf(stderr, ERR_STR "Unable to wait for child process (PID %i): %s" CLR_STR "\n", children[i], strerror(errno));
+                    critical("Unable to wait for child process (PID %i)", children[i]);
                 } else if (ret == children[i]) {
                     children[i] = 0;
                     if (status != 0) {
-                        fprintf(stderr, ERR_STR "Child process with PID %i terminated with exit code %i" CLR_STR "\n", ret, status);
+                        critical("Child process with PID %i terminated with exit code %i", ret, status);
                     }
                 }
             }