HTTP Status Codes
Searchable reference for every HTTP response code (1xx informational through 5xx server error) with concise explanations and RFC references.
About HTTP Status Codes
HTTP status codes are three-digit numbers sent by a server in the first line of its response, telling the client whether the request succeeded, requires further action, or failed. They are defined primarily in RFC 9110 (replacing the older RFC 7231/2616), with additional codes registered in the IANA registry.
The Five Classes
- 1xx — Informational: request received, processing continues. Rarely seen by application code.
- 2xx — Success: request succeeded.
200 OKis the default;201 Created,204 No Content, and206 Partial Contenthave specific meanings. - 3xx — Redirection: client must take further action.
301/308are permanent;302/307are temporary;304 Not Modifiedmeans the cached version is still good. - 4xx — Client error: the request looks wrong.
400,401,403,404, and429are the most common. - 5xx — Server error: the server failed.
500 Internal Server Erroris the catch-all;502,503, and504usually indicate upstream/load issues.