diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..bdd62fa
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Oleksandr Zhylin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
\ No newline at end of file
diff --git a/src/client.c b/src/client.c
index 523a93b..c0b0fc3 100644
--- a/src/client.c
+++ b/src/client.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "client.h"
 #include "file_p.h"
 #include "main.h"
diff --git a/src/client.h b/src/client.h
index 9b515a8..8d49da6 100644
--- a/src/client.h
+++ b/src/client.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef CLIENT_H
 #define CLIENT_H
 
diff --git a/src/db.c b/src/db.c
index 4dcb2e6..2df2511 100644
--- a/src/db.c
+++ b/src/db.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "db.h"
 #include "main.h"
 #include <endian.h>
diff --git a/src/db.h b/src/db.h
index 960f09f..b704b38 100644
--- a/src/db.h
+++ b/src/db.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef DB_H
 #define DB_H
 #include "main.h"
diff --git a/src/file_p.c b/src/file_p.c
index 5fadf31..5cd23fe 100644
--- a/src/file_p.c
+++ b/src/file_p.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "file_p.h"
 #include "db.h"
 #include "main.h"
diff --git a/src/file_p.h b/src/file_p.h
index 394ab5d..14d3d52 100644
--- a/src/file_p.h
+++ b/src/file_p.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef FILEP_H
 #define FILEP_H
 #include "main.h"
diff --git a/src/main.c b/src/main.c
index 9c3adc6..ef1a2c2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "main.h"
 #include "server.h"
 #include "db.h"
diff --git a/src/main.h b/src/main.h
index 71e89ca..3b9595d 100644
--- a/src/main.h
+++ b/src/main.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef MAIN_H
 #define MAIN_H
 #include <stddef.h>
diff --git a/src/server.c b/src/server.c
index 62d8f8f..e065124 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "main.h"
 #include "session.h"
 #include "user.h"
diff --git a/src/server.h b/src/server.h
index a370e5c..4c759ba 100644
--- a/src/server.h
+++ b/src/server.h
@@ -1,8 +1,11 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef SERVER_H
 #define SERVER_H
 #include "main.h"
-int start_server();
-char *get_welcome_mes();
+int start_server(void);
+char *get_welcome_mes(void);
 void server_main_loop(server_data_t *);
 void prepare_start(int argc, char *argv[]);
 #endif
\ No newline at end of file
diff --git a/src/session.c b/src/session.c
index 876fe34..27bc793 100644
--- a/src/session.c
+++ b/src/session.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "session.h"
 #include "client.h"
 #include "db.h"
diff --git a/src/session.h b/src/session.h
index 3e3c55d..f4f2db6 100644
--- a/src/session.h
+++ b/src/session.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef SESSION_H
 #define SESSION_H
 #include "main.h"
diff --git a/src/types.h b/src/types.h
index 61eb662..40bbabd 100644
--- a/src/types.h
+++ b/src/types.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef D_TYPES_H
 #define D_TYPES_H
 
diff --git a/src/user.c b/src/user.c
index 8895634..809b218 100644
--- a/src/user.c
+++ b/src/user.c
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #include "db.h"
 #include "main.h"
 #include "session.h"
@@ -8,7 +11,7 @@
 
 int32_t create_user(session *sess, char *line) {
   i_db_user_create p;
-  uint32_t privileges;
+  int32_t privileges;
   int32_t res;
   if (sscanf(line, "register %s %s %s", p.uname, p.pass, p.email) == 3) {
     res = db_user_create(&p);
diff --git a/src/user.h b/src/user.h
index c4dfb9d..33e09bb 100644
--- a/src/user.h
+++ b/src/user.h
@@ -1,3 +1,6 @@
+/* SPDX-License-Identifier: MIT */
+/* Copyright (c) 2026 Oleksandr Zhylin */
+
 #ifndef USER_H
 #define USER_H