HTTP Status Codes

Complete searchable reference of all HTTP status codes with descriptions

What is it and how does it work?

This is a searchable reference for every HTTP status code — the three-digit numbers a server returns to say what happened with a request, like 200 OK, 404 Not Found or 500 Internal Server Error. Every web page load, API call and form submission comes back with one of these codes, and knowing what each means is the fastest way to understand why something worked or failed. Instead of guessing what "418" or "429" signifies, you look it up and get a clear description of what the server is telling you.

The codes are organised into five classes by their first digit, and that grouping is the key to reading them at a glance: 1xx are informational, 2xx mean success, 3xx are redirects, 4xx are client errors (the request was wrong), and 5xx are server errors (the server failed). That single distinction — is this my fault or the server's? — usually points you straight at where to look. This reference lets you search by number or keyword to find the exact meaning, with the common everyday codes and the obscure ones all in one place.

Common use cases

• Debugging an API call: look up the code your request returned to understand whether the problem is your request (4xx) or the server (5xx).
• Understanding a redirect: check the difference between 301 and 302 to handle a moved page correctly.
• Handling rate limits: confirm what 429 means and how to respond when an API tells you that you have sent too many requests.

Frequently asked questions

What do the 4xx and 5xx ranges mean?

4xx codes are client errors — the request itself was wrong, such as 404 Not Found or 400 Bad Request, so the fix is usually on your side. 5xx codes are server errors, such as 500 or 503, meaning the request was valid but the server failed to handle it.

What is the difference between 301 and 302?

Both are redirects, but 301 is permanent — the resource has moved for good, and clients and search engines should update their links. 302 is temporary, meaning the original URL should still be used in future. Using the wrong one can affect SEO and caching.

What does a 401 versus a 403 mean?

401 Unauthorized means you are not authenticated — you need to log in or provide valid credentials. 403 Forbidden means you are authenticated but not allowed to access the resource. One is about who you are; the other is about your permissions.

What should I do when I get a 429?

429 Too Many Requests means you have hit a rate limit. The correct response is to slow down and retry later, ideally honouring any Retry-After header the server sends, rather than hammering the endpoint, which only prolongs the limit.

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