HTTP Status Codes Reference
Complete reference for all HTTP status codes — 1xx Informational, 2xx Success, 3xx Redirects, 4xx Client Errors, 5xx Server Errors. Search and filter instantly.
Understanding HTTP Status Codes
HTTP status codes are 3-digit numbers issued by a server in response to a client's request. They are grouped by the first digit: 1xx (informational), 2xx (successful), 3xx (redirection), 4xx (client error), and 5xx (server error).
Most important status codes for APIs
In REST API design, the most important codes are: 200 OK, 201 Created, 204 No Content, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 409 Conflict, 422 Unprocessable Content, 429 Too Many Requests, and 500 Internal Server Error.
What is the difference between 401 and 403?
401 means the client is not authenticated — no credentials or invalid credentials were provided. 403 means the client IS authenticated but does not have permission. Use 401 for "please log in" and 403 for "you are logged in but not allowed".
When should I use 301 vs 308?
Use 301 for permanent URL changes on websites where the method can change to GET (browser follows redirect). Use 308 for REST APIs where you need the method to stay the same (a POST stays a POST after the redirect).