HTTP Status Codes Reference

The server has received the request headers and the client should proceed to send the request body.

Common use: Used in HTTP/1.1 for large request bodies with Expect: 100-continue header.

The server is switching protocols as requested by the client.

Common use: WebSocket upgrade from HTTP.

The server has received and is processing the request, but no response is available yet.

Common use: WebDAV; prevents client timeout on long operations.

Used to return some response headers before the final response.

Common use: Preload resources before the full response is ready.

The request has succeeded.

Common use: Standard response for successful HTTP requests.

The request has been fulfilled and a new resource has been created.

Common use: POST requests that create a new resource (user, record, file).

The request has been accepted for processing, but processing has not been completed.

Common use: Async operations — job queued but not yet processed.

The server successfully processed the request but is not returning any content.

Common use: DELETE requests, PUT updates that need no response body.

The server is delivering only part of the resource due to a range header.

Common use: Video streaming, resumable downloads.

Provides status for multiple independent operations.

Common use: WebDAV; batch operations with mixed results.

The resource has been permanently moved to a new URL.

Common use: URL changes, domain migrations. Search engines update their index.

The resource is temporarily located at a different URL.

Common use: Temporary redirects (login → dashboard). Often misused — use 307 instead.

The response can be found under a different URL using GET.

Common use: After POST form submission, redirect to GET result page (PRG pattern).

The resource has not been modified since the last request.

Common use: Browser caching with If-Modified-Since or ETag headers.

The request should be repeated with the same method at another URL.

Common use: Like 302 but guarantees method and body are preserved.

The resource has permanently moved, method and body preserved.

Common use: Like 301 but guarantees POST stays POST.

The server cannot process the request due to malformed syntax.

Common use: Invalid JSON, missing required fields, validation errors.

Authentication is required and has failed or has not been provided.

Common use: Missing or invalid auth token/credentials.

The server understood the request but refuses to authorize it.

Common use: User is authenticated but lacks permission for this resource.

The requested resource could not be found on the server.

Common use: Invalid URL, deleted resource, typo in endpoint.

The HTTP method is not allowed for the requested resource.

Common use: Sending POST to a GET-only endpoint.

The server cannot produce a response matching the Accept headers.

Common use: Content negotiation failure (requesting XML from JSON-only API).

The server timed out waiting for the request.

Common use: Client took too long to send the complete request.

The request conflicts with the current state of the resource.

Common use: Duplicate entry, edit conflict, concurrent modification.

The resource is no longer available and will not be available again.

Common use: Permanently deleted resource — unlike 404, this is intentional.

The request entity is larger than the server is willing to process.

Common use: File upload exceeds size limit.

The media type of the request is not supported.

Common use: Sending form data to an endpoint that expects JSON.

The request is well-formed but semantically incorrect.

Common use: Validation errors — email format wrong, date in past, etc.

The user has sent too many requests in a given time period.

Common use: Rate limiting. Check Retry-After header.

The resource is unavailable due to legal demands.

Common use: GDPR compliance, government censorship, DMCA takedowns.

The server encountered an unexpected condition that prevented it from fulfilling the request.

Common use: Unhandled exception, bug in server code, database error.

The server does not support the functionality required to fulfill the request.

Common use: API endpoint exists but feature is not yet built.

The server received an invalid response from an upstream server.

Common use: Reverse proxy (Nginx) cannot reach the app server.

The server is temporarily unable to handle the request.

Common use: Server overloaded, maintenance mode, deployment in progress.

The server did not receive a timely response from an upstream server.

Common use: Upstream service is too slow — database timeout, external API timeout.