HTTP Status Codes Explained

Every HTTP response includes a three-digit status code that tells the client what happened. The first digit defines the class of response:

• 1xx — Informational: the request is being processed
• 2xx — Success: the request was received and accepted
• 3xx — Redirection: further action is needed
• 4xx — Client Error: the request has a problem
• 5xx — Server Error: the server failed to fulfill a valid request

• 200 OK — Standard success response. The body contains the requested resource.
• 201 Created — A new resource was created, typically after a POST request.
• 204 No Content — Success with no response body, common for DELETE requests.
• 206 Partial Content — The server is returning part of a resource, used for range requests (like resuming downloads).

• 301 Moved Permanently — The resource has a new permanent URL. Search engines transfer SEO value. Use for domain migrations.
• 302 Found — Temporary redirect. The original URL should still be used for future requests.
• 304 Not Modified — The cached version is still valid. Saves bandwidth by skipping the response body.
• 307 Temporary Redirect — Like 302 but preserves the HTTP method (POST stays POST).

• 400 Bad Request — Malformed syntax, invalid parameters, or missing required fields.
• 401 Unauthorized — Authentication is required. The client must provide credentials.
• 403 Forbidden — The server understood the request but refuses to authorize it.
• 404 Not Found — The requested resource does not exist.
• 405 Method Not Allowed — The HTTP method (GET, POST, etc.) is not supported for this endpoint.
• 409 Conflict — The request conflicts with the current state (e.g., duplicate resource).
• 429 Too Many Requests — Rate limit exceeded. Check the Retry-After header.

• 500 Internal Server Error — A generic catch-all for unexpected server failures.
• 502 Bad Gateway — The server acting as a proxy received an invalid response from upstream.
• 503 Service Unavailable — The server is temporarily overloaded or under maintenance.
• 504 Gateway Timeout — The proxy server did not receive a timely response from upstream.