mrtran
Aug 18, 2025

HTTP Status Codes

HTTP status codes are three-digit responses returned by a server when a client (like a browser or API call) makes a request. They are grouped into categories by their first digit.

1xx – Informational

These indicate the request is received and processing is continuing.

  • 100 Continue – Request received, client should continue.

  • 101 Switching Protocols – Server is switching protocols as requested.

  • 102 Processing – Server has received the request and is processing, but no response yet.

2xx – Success

These mean the request was successfully received and processed.

  • 200 OK – Request succeeded.

  • 201 Created – Resource successfully created.

  • 202 Accepted – Request accepted but not yet processed.

  • 204 No Content – Request succeeded, but no content returned.

  • 206 Partial Content – Partial response (e.g., when using ranges).

3xx – Redirection

These indicate the client must take additional steps.

  • 301 Moved Permanently – Resource moved to a new permanent URL.

  • 302 Found – Temporary redirect.

  • 303 See Other – Redirect to another resource (commonly after POST).

  • 304 Not Modified – Resource not changed, use cached version.

  • 307 Temporary Redirect – Temporary redirect, same method.

  • 308 Permanent Redirect – Permanent redirect, same method.

4xx – Client Errors

These indicate an error in the client’s request.

  • 400 Bad Request – Malformed or invalid request.

  • 401 Unauthorized – Authentication required or failed.

  • 403 Forbidden – Client does not have permission.

  • 404 Not Found – Resource not found.

  • 405 Method Not Allowed – HTTP method not supported for this resource.

  • 408 Request Timeout – Server timed out waiting for request.

  • 409 Conflict – Request conflicts with resource state.

  • 410 Gone – Resource is permanently removed.

  • 429 Too Many Requests – Client sent too many requests (rate limiting).

5xx – Server Errors

These indicate the server failed to fulfill a valid request.

  • 500 Internal Server Error – Generic server error.

  • 501 Not Implemented – Server does not support the request method.

  • 502 Bad Gateway – Server received an invalid response from upstream.

  • 503 Service Unavailable – Server unavailable (overloaded or maintenance).

  • 504 Gateway Timeout – Server didn’t receive a timely response.

  • 505 HTTP Version Not Supported – Server doesn’t support the HTTP version used.

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