HTTP Status Code Lookup — All Status Codes Explained

An HTTP status code is a 3-digit number sent by a server in response to a client request. The first digit indicates the class of response: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error. Browsers, APIs, and monitoring tools all use these codes to understand what happened with a request.

200 OK — request succeeded. 201 Created — resource created (use after POST). 301/302 — permanent/temporary redirect. 400 Bad Request — malformed client request. 401 Unauthorized — not authenticated. 403 Forbidden — authenticated but no permission. 404 Not Found — resource doesn't exist. 422 Unprocessable Entity — validation errors. 429 Too Many Requests — rate limited. 500 Internal Server Error — server crashed. 503 Service Unavailable — server overloaded or down.

401 Unauthorized means the request lacks valid authentication credentials — the server doesn't know who you are. 403 Forbidden means the server knows who you are but you don't have permission to access the resource. In short: 401 = not logged in, 403 = logged in but not allowed.