HTTP Status Code Lookup

About HTTP Status Code Lookup

Every HTTP response includes a three-digit status code indicating what happened to the request — and while a handful of codes (200, 404, 500) are famous enough that most developers know them by heart, the full standard includes dozens of codes covering much more specific situations, each with a precise, standardized meaning defined by HTTP specifications maintained by the IETF. Knowing exactly what a less common code means, rather than guessing from context, is often the fastest way to understand why an API call failed or behaved unexpectedly.

This reference organizes codes into their standard categories, each identifiable by its first digit: 2xx codes indicate success (the request was received, understood, and accepted); 3xx codes indicate redirection (further action is needed to complete the request, usually automatically by the browser or HTTP client); 4xx codes indicate a client error (something about the request itself was wrong — bad syntax, missing authentication, a resource that doesn't exist); and 5xx codes indicate a server error (the request was valid, but the server failed to fulfill it). Recognizing which category a code falls into, even before reading its specific meaning, immediately tells you whether to look at your request or suspect a problem on the server's end.

Beyond the famous few, this reference covers status codes that come up constantly in real API work but are less universally memorized: 429 (Too Many Requests, for rate limiting), 422 (Unprocessable Entity, for a request that's syntactically valid JSON but fails business logic validation), 304 (Not Modified, for HTTP caching), and 502/503/504 (the distinct flavors of "something's wrong upstream or the server's overloaded" that often get lumped together as "the API is down" without understanding which specific failure occurred).

Use the search box to jump straight to a code by number or by name — typing "404" or "not found" both find the same entry — which is faster than scanning a long static reference table when you already know roughly what you're looking for.

How it works

1. Search by code or name. Type a status code number or part of its name to filter instantly.
2. Read the meaning. Each entry shows its category color, official name, and a plain-language explanation.