Searchable reference for all HTTP status codes with causes and fixes.
The HTTP Status Code Reference lists standard and common HTTP status codes from 1xx (informational) through 5xx (server error), with short explanations, typical causes, and remediation tips. Developers use it when they see an unfamiliar code (e.g. 429, 503) or when implementing APIs and need to choose the right code. Searchable and filterable by range or keyword.
502 Bad Gateway means the server got an invalid response from an upstream server; 504 Gateway Timeout means the upstream did not respond in time.
201 Created is for successful creation of a resource (e.g. POST that creates something); 200 OK is for successful GET or generic success.
We list RFC-defined and widely used codes; some servers use non-standard codes (e.g. 420) which may be documented separately.
Some references include example requests; for live testing use the Status Checker or Request Builder.
Use our HTTP Status Code Checker or Request Builder to hit a URL and see the live code.