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HTTP Status Codes

Every standard HTTP status code in one searchable list — what it means, when to return it from your API, and what the response looks like.

Category

62 status codes

404

Not Found

4xx · Client error · RFC 9110

What it means

The server can't find the requested resource.

When to use it

A wrong URL, a deleted page or a record ID that doesn't exist.

Example response

HTTP/1.1 404 Not Found
Content-Type: application/json

{
  "status": 404,
  "error": "Not Found",
  "message": "The server can't find the requested resource."
}

Quick reference

1xx
Informational — Request received, still processing
2xx
Success — Request received, understood and accepted
3xx
Redirection — Further action needed to complete the request
4xx
Client error — The request has a problem the client must fix
5xx
Server error — The server failed to handle a valid request

  • Complete reference

    All registered codes from 100 to 511, with the RFC that defines each one and older names you might still see.

  • Fast search

    Search by number, name or keyword like “timeout” or “redirect”, and filter by class.

  • Practical examples

    A plain-English “when to use it” and a realistic example response for every code.

HTTP status codes explained

Every HTTP response starts with a three-digit status code that tells the browser or API client what happened. Returning the right code makes your API easier to use, helps search engines index your site correctly and makes bugs much faster to track down.

The five classes

  • 1xx Informational: the request was received and is still being processed.
  • 2xx Success: the request worked — 200 OK, 201 Created, 204 No Content.
  • 3xx Redirection: the client needs to go somewhere else, such as a moved page.
  • 4xx Client error: something is wrong with the request — bad input, no login, no permission or a missing page.
  • 5xx Server error: the request was fine but the server failed to handle it.

Codes people often mix up

  • 401 vs 403:401 means “we don't know who you are — log in”. 403 means “we know who you are, and you're not allowed”.
  • 301 vs 302 vs 307/308: 301 and 308 are permanent, 302 and 307 are temporary. 307 and 308 also guarantee the method and body stay the same.
  • 400 vs 422:use 400 for requests you can't parse and 422 for well-formed requests that fail validation.
  • 502 vs 504:both come from a proxy. 502 means the upstream sent a bad response; 504 means it didn't answer in time.

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