HTTP Status Codes

How to use

1. 1Type a code (for example, 404, 503, or 422) or a phrase (gateway, redirect, rate limit) into the search box. The list filters live as you type.
2. 2Use the class filter chips (1xx through 5xx) to narrow the list to a single response class.
3. 3Click any status card to pin it as the active selection. The detail panel at the top shows class, summary, full explanation, RFC reference, cacheability, and a real example where one applies.
4. 4Use Copy code to copy just the number, or Copy code + phrase to copy the standard "404 Not Found" form for documentation, error messages, or status pages.
5. 5Read the Status code classes panel at the bottom for a quick map of what each leading digit means.

About this tool

HTTP Status Codes is a fast, browser-only reference for every status code defined by the HTTP specifications, organized into the five classes the standard recognizes: 1xx informational (request received, server is still working), 2xx success (the request was understood and accepted), 3xx redirection (the client must take additional action, usually following a Location header), 4xx client error (the request was bad in some way), and 5xx server error (the server failed to fulfill an otherwise valid request). Each entry shows the numeric code, the official reason phrase, the response class, a one-line summary you can scan, a longer explanation that covers when to use it correctly, the controlling RFC (mostly RFC 9110 for the core codes plus RFC 4918 for WebDAV, RFC 6585 for additional codes like 428 and 429, RFC 7725 for 451, and RFC 8297 for 103 Early Hints), and whether the response is cacheable by default, only with explicit caching headers, or never. Many entries include a concrete example so you can see how the code looks in real API or browser traffic, and the detail section pulls out the design questions most teams hit, like 401 versus 403 (authentication versus authorization), 301 versus 308 (preserving the request method on redirect), 400 versus 422 (syntactic versus semantic problems with the body), and 429 with Retry-After for rate limiting. The header search box accepts both a numeric code (404, 503, 422) and a phrase (gateway, redirect, rate limit, teapot), and typing a known three-digit code automatically opens its detail card. Class filter chips narrow the list to a single class so you can scan only redirections or only client errors. Cards are color coded by class (sky for 1xx, emerald for 2xx, violet for 3xx, amber for 4xx, rose for 5xx) and clicking any card pins it as the active selection at the top of the page, where you can copy just the code or the full code plus phrase for use in API documentation, error messages, or status pages. This is a reference tool, not a request-runner: it does not send HTTP requests on your behalf and never connects to a remote server, which means the lookup works offline, never logs your queries, and never delays a response on a slow network. Useful for API designers picking the right code for a new endpoint, frontend engineers chasing a 504 in production, support engineers explaining a 451 to a customer, security reviewers auditing 403 versus 401 leaks, technical writers drafting error documentation, and anyone who wants a clean, accurate map of how HTTP signals success, failure, redirection, and the long tail in between.

Free to use. Works in your browser. No signup, no login.