HTTP Status Code Lookup
Look up any HTTP status code's meaning, category and common usage. Search by number or keyword across 1xx to 5xx — instant reference for developers.
About the HTTP Status Code Lookup
This HTTP status code lookup is a fast, searchable reference for every standard response code from 1xx informational through 5xx server errors. Type a number like 404, 301 or 502, or search by keyword such as 'redirect', 'rate limit' or 'forbidden', and get the code's name, category and a plain-English explanation of what it means and when it's used.
Each entry explains the practical context developers actually need: why a 401 really means unauthenticated, when to send 307 instead of 302 to preserve the request method, why a 502 points at a crashed upstream server, and how 422 became the go-to validation-error response in REST APIs. Codes are grouped by class with a short description of each category.
The whole reference is bundled into the page, so search is instant and works offline — no API calls, no waiting. Copy any code and name with one click for commit messages, tickets or documentation.
How to Use the HTTP Status Code Lookup
- 1Type a status code number, or a keyword like 'timeout' or 'redirect'.
- 2Browse the matching results grouped by category (1xx–5xx).
- 3Read the meaning and common usage for each code.
- 4Copy a code and name for your notes or tickets.
Frequently Asked Questions
What's the difference between 401 and 403?
401 Unauthorized means you're not authenticated — the server doesn't know who you are, so send valid credentials. 403 Forbidden means you are authenticated but not allowed to access this resource. In short: 401 is 'log in', 403 is 'you can't do that'.
When should I use 301 vs 302 vs 308?
301 is a permanent redirect that search engines follow and cache, but browsers may change the method to GET. 302 is temporary with the same method caveat. Use 308 for permanent redirects that must preserve the HTTP method and body (important for APIs), and 307 for the temporary equivalent.
What does a 502 Bad Gateway actually mean?
A gateway or reverse proxy (nginx, a load balancer or a CDN) received an invalid or empty response from the upstream server it forwarded your request to. It usually means the backend crashed, is overloaded or is unreachable — check the application server, not the proxy.
Why do APIs return 422 instead of 400?
400 Bad Request means the request itself is malformed (bad JSON syntax, for example). 422 Unprocessable Content means the syntax is fine but the data fails validation rules — a required field is missing or a value is out of range. Many REST frameworks use 422 for these semantic validation errors.
Is 418 'I'm a teapot' a real status code?
It's a real, registered code from an April Fools' RFC (the Hyper Text Coffee Pot Control Protocol). It isn't used for normal web traffic, though some sites return it playfully. It's included here for completeness.