HTTP Status Codes
Every common HTTP status code, grouped by class. Search to filter.
A searchable reference of every HTTP status code — 1xx through 5xx — with short explanations. Find out what 404, 403, 500 or 418 really mean when you see them in a browser or API response.
Reference: IANA HTTP Status Code Registry.
How to use the HTTP Status Codes Reference
- Search for a code (like 404) or a phrase (like 'teapot').
- Browse by class: 2xx success, 4xx client errors and so on.
- Read the meaning of any code at a glance.
Frequently asked questions
What does 404 mean?
Not Found — the server cannot find the requested resource. It is the most common client error.
What does 500 mean?
Internal Server Error — the server crashed while handling the request; a server-side bug, not your fault.
What is the difference between 301 and 302?
301 is a permanent redirect (cacheable, passes SEO value); 302 is temporary.
What does 418 I'm a Teapot mean?
An April Fools' joke from 1998 that became a beloved easter egg in HTTP lore.
Fun facts about HTTP Status Codes
- The HTTP 404 error is named after Room 404 at CERN, where the original web servers were located — though this is actually a popular myth with no confirmed evidence.
- HTTP 418 'I'm a teapot' comes from an April Fools' RFC (2324, 1998) about controlling coffee pots; Google once served a 418 page at google.com/teapot.
- Google says both 301 (permanent) and 302 (temporary) redirects pass ranking signals; the difference is which URL it tends to show: the new one for a 301, often the original for a 302.
- HTTP 503 (Service Unavailable) is the correct status to return during maintenance — it tells search engines to come back later rather than removing the page from their index.
- The HTTP specification was created by Tim Berners-Lee in 1991, and the first version (HTTP/0.9) only supported GET requests — no headers, no status codes.