HTTP Status Code Lookup
Type a code such as 404, a class such as 5xx, or words such as redirect, rate limit or teapot. Each entry gives the meaning in plain English, common causes and fixes, the defining RFC, whether it is cacheable by default and whether retrying is safe. Unofficial codes from servers and CDNs are clearly labelled. The reference is built into the page, so nothing you type leaves your browser.
| Code | Status | Meaning, causes and fixes |
|---|
How to use
- Type a status code (404), a class (4xx), a partial code (50 or 40x) or words such as redirect, timeout or rate limit. Results update as you type.
- You can also paste text such as HTTP 503 or 404 Not Found; the code is picked out for you.
- Click a class chip to list only 1xx, 2xx, 3xx, 4xx or 5xx codes, or Unofficial to see codes that are not in the IANA registry.
- Read the badges: IANA or Unofficial (with who sends it), Cacheable by default, and the retry advice.
- For any number from 100 to 599, the line above the results gives its class and says whether IANA has assigned it.
Examples
Not Found — 4xx Client Error, RFC 9110 §15.5.5, cacheable by default; fix the URL rather than retrying.
429 Too Many Requests (wait for Retry-After) and Twitter's old unofficial 420 Enhance Your Calm.
All server error codes, from 500 Internal Server Error to Cloudflare's 520–530 and the proxy codes 598 and 599.
In the 2xx (Successful) class but not assigned by IANA; clients treat it like 200.
Supported formats
- Input: a three-digit code (100–599), a class written 4xx, a prefix such as 50 or a pattern such as 40x, or one or more words matched against names, meanings and causes.
- Every code in the IANA HTTP Status Code Registry (RFC 9110, WebDAV, RFC 6585 and others), including the reserved 306 and 418 and the temporary 104, plus widely seen unofficial codes from nginx, Cloudflare, AWS load balancers, Microsoft IIS, Laravel and others.
Privacy
This tool runs entirely in your browser. Nothing you enter or open is sent anywhere. Privacy policy.
Limitations
- Unofficial codes mean different things to different products (499 is a closed connection in nginx but a missing token in ArcGIS). Check which server or service sent the response.
- The retry advice is a general rule. Whether a retry is safe also depends on the method and on the API; a POST that timed out may already have been processed.
- Cacheable by default lists the codes RFC 9110 allows caches to store heuristically. Cache-Control and Expires headers on the actual response always take precedence.
- The IANA registry was checked in October 2026; the temporary 104 registration may lapse or change.
FAQ
What is the difference between 401 and 403?
401 Unauthorized means the request has no valid credentials, so logging in or refreshing a token may fix it. 403 Forbidden means the server knows who you are (or doesn't care) and still refuses, so logging in again usually won't help.
Should I use 301, 302, 307 or 308 for a redirect?
Use 301 or 308 for permanent moves and 302 or 307 for temporary ones. 307 and 308 guarantee the method and body are kept, so a POST stays a POST; with 301 and 302 browsers may switch to GET. Use 303 after a form POST to send the user to a result page.
What happens with a status code that isn't registered?
RFC 9110 says a client that doesn't recognise a code must treat it like the x00 code of its class, so an unknown 4xx is handled like 400 and an unknown 5xx like 500. Codes above 599 are not valid HTTP status codes.
Is 418 I'm a teapot a real status code?
It started as an April Fools' joke (RFC 2324). IANA lists 418 as reserved (Unused) and RFC 9110 keeps it from being reassigned because so many programs use it, but it has no official meaning.