HTTP Status Code Lookup

HTTP statuses split by the first digit. 1xx Informational signals interim states like Continue or Switching Protocols. 2xx Success means the request worked (200 OK, 201 Created, 204 No Content). 3xx Redirection points the client elsewhere (301, 302, 304, 307, 308). 4xx Client Error blames the request (400 Bad Request, 401 Unauthorized, 404 Not Found, 429 Too Many Requests). 5xx Server Error blames the server (500 Internal Server Error, 502 Bad Gateway, 503 Service Unavailable, 504 Gateway Timeout). RFC 9110 is the current canonical reference for the core set.

Both indicate success. A 200 response can carry representation data, while a 204 response ends after its headers and cannot contain content. A 204 can fit an update or analytics endpoint that needs no response body. A tracking-pixel request normally needs an image response instead.

301 Moved Permanently and 308 Permanent Redirect signal a permanent move. 302 Found and 307 Temporary Redirect signal a temporary one. Search engines make canonicalization and indexing decisions from the full context, not from a status alone. The other axis is method preservation: 301 and 302 were historically allowed to rewrite POST to GET, while 307 and 308 must preserve the original method. Use 308 for permanent moves of POST endpoints, 307 for temporary redirects of non-GET requests, and 301 for a permanent GET URL move.

RFC 2324 defined 418 as part of an April Fools' protocol. In the current HTTP semantics registry, 418 is reserved as unused rather than assigned normal HTTP semantics. Some applications still return it as a custom signal, so interpret it using that service's documentation.

429 means the client exceeded a rate limit. The response may include Retry-After; when present, honor it. Otherwise follow the API's documented retry policy and use bounded exponential backoff with jitter. Avoid automatic retries for non-idempotent requests unless the API provides a safe idempotency mechanism.