HTTP Status Codes Explained: 2xx, 3xx, 4xx and 5xx
October 5, 2026 · 1 min read
Every HTTP response starts with a three-digit status code. The first digit tells you the class of result.
2xx: success
200 OK means the request worked. 201 Created is returned after creating a resource and 204 No Content after a successful delete.
3xx: redirection
301 is a permanent move and passes SEO value to the new URL. 302 is temporary. 304 Not Modified tells the client its cached copy is still good.
4xx: client errors
400 means the request is malformed, 401 means you are not authenticated, 403 means you are authenticated but not allowed, and 404 means the resource does not exist. 422 signals validation errors and 429 tells you to slow down.
5xx: server errors
500 is a generic server failure. 502 and 504 come from gateways that could not get a timely answer from the upstream server, and 503 means the service is temporarily unavailable.
Browse all codes in our HTTP status code reference, and use a monitor to be alerted the moment your endpoints start returning 5xx errors.