HTTP Status Code Reference

Complete reference of every HTTP status code and what it means.

Informational

100ContinueServer received headers, client should continue with request body.

101Switching ProtocolsServer is switching protocols as requested by client.

Success

200OKRequest succeeded. Standard response for successful HTTP requests.

201CreatedRequest succeeded and a new resource was created.

202AcceptedRequest accepted for processing, but processing not complete.

204No ContentRequest succeeded but no content to return.

206Partial ContentServer delivering only part of resource due to range header.

Redirection

301Moved PermanentlyResource permanently moved to a new URL.

302FoundResource temporarily at a different URL.

304Not ModifiedResource not modified since last request — use cached version.

307Temporary RedirectTemporary redirect, method and body should not change.

308Permanent RedirectPermanent redirect, method and body should not change.

Client Error

400Bad RequestServer cannot process request due to client error.

401UnauthorizedAuthentication required and has failed or not been provided.

403ForbiddenServer understood request but refuses to authorize it.

404Not FoundRequested resource could not be found on the server.

405Method Not AllowedRequest method not supported for the requested resource.

408Request TimeoutServer timed out waiting for the request.

409ConflictRequest conflicts with current state of the server.

410GoneResource permanently removed, no forwarding address.

413Payload Too LargeRequest entity larger than server is willing to process.

415Unsupported Media TypeMedia format of requested data not supported.

422Unprocessable EntityRequest well-formed but contains semantic errors.

429Too Many RequestsUser has sent too many requests in given time (rate limiting).

Server Error

500Internal Server ErrorGeneric error when server encounters unexpected condition.

501Not ImplementedServer does not support functionality required.

502Bad GatewayServer acting as gateway got an invalid response upstream.

503Service UnavailableServer not ready to handle request — often maintenance/overload.

504Gateway TimeoutServer acting as gateway did not get timely response upstream.

511Network Authentication RequiredClient needs to authenticate to gain network access.

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HTTP Status Code Reference — Free Developer Utility

HTTP Status Code Reference lists every standard status code returned by web servers, organized by category — informational (1xx), success (2xx), redirection (3xx), client error (4xx), and server error (5xx) — with a plain-English explanation of what each one signals. Status codes are the first thing to check when debugging API integrations, unexpected redirects, or failed requests, but memorizing all of them is unnecessary when you have a quick reference. This page covers the codes developers encounter daily (200 OK, 301/302 redirects, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 429 Too Many Requests, 500 Internal Server Error, 502 Bad Gateway, 503 Service Unavailable) as well as less common but still important codes, each with a short description of the typical cause and how a client should respond.

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Frequently Asked Questions

401 Unauthorized means authentication is required or has failed — the client isn't properly identified. 403 Forbidden means the client IS identified but doesn't have permission to access the resource.

502 Bad Gateway usually means a proxy or load balancer got an invalid response from an upstream server. 503 Service Unavailable typically means the server is overloaded or down for maintenance.

No — it's a success-adjacent redirection code meaning the browser's cached version is still valid, so the server doesn't need to resend the full response, saving bandwidth.

429 Too Many Requests is the standard code for rate limiting, typically paired with a Retry-After header telling the client when to try again.