loot.tools

HTTP Status Codes

Look up any HTTP status code by number, name, or meaning. Codes are grouped by class from 1xx informational through 5xx server errors, each with a plain-English explanation.

4xx Client Error

400
Bad Request
The server can't process the request due to a client error like malformed syntax.
401
Unauthorized
Authentication is required and has failed or not been provided.
402
Payment Required
Reserved for future use, sometimes used by APIs for billing or rate limits.
403
Forbidden
The server understood the request but refuses to authorize it.
404
Not Found
The server can't find the requested resource. The classic broken link.
405
Method Not Allowed
The request method is known but not supported for this resource.
406
Not Acceptable
The server can't produce a response matching the Accept headers.
407
Proxy Authentication Required
Authentication with a proxy is needed before the request can proceed.
408
Request Timeout
The server timed out waiting for the request.
409
Conflict
The request conflicts with the current state of the resource.
410
Gone
The resource is permanently gone with no forwarding address.
411
Length Required
The server requires a Content-Length header that wasn't provided.
412
Precondition Failed
A precondition in the request headers evaluated to false.
413
Payload Too Large
The request body is larger than the server is willing to process.
414
URI Too Long
The requested URL is longer than the server will interpret.
415
Unsupported Media Type
The request's media format isn't supported by the server.
416
Range Not Satisfiable
The requested range can't be fulfilled for the resource.
417
Expectation Failed
The expectation in the Expect header couldn't be met.
418
I'm a Teapot
An April Fools' joke from 1998. The server refuses to brew coffee.
422
Unprocessable Entity
The request was well-formed but had semantic errors, common in form validation.
425
Too Early
The server is unwilling to process a request that might be replayed.
426
Upgrade Required
The client should switch to a different protocol.
428
Precondition Required
The server requires the request to be conditional to avoid lost updates.
429
Too Many Requests
The client sent too many requests in a given time, hitting a rate limit.
431
Request Header Fields Too Large
The server won't process the request because its headers are too large.
451
Unavailable For Legal Reasons
The resource is blocked for legal reasons like a government takedown.

5xx Server Error

What this is

A complete, searchable list of HTTP response status codes. Type a number like 404, a name like 'forbidden', or a keyword like 'timeout' to filter instantly. Each code includes a short explanation of what it signals and when a server sends it. Codes are color-coded by class so you can scan for the group you need.

How status codes are grouped

Status codes fall into five classes based on their first digit. 1xx means informational, the request is being processed. 2xx means success. 3xx means redirection, the client needs to take another step. 4xx means a client error like a bad request or missing resource. 5xx means a server error where something broke on the server side.

When you'd use this

  • You're building or debugging an API and need to pick the right code for a response
  • Or your app returned a 422 and you want to know what it actually means
  • Or you hit a 503 and need to explain it to a teammate
  • Instead of digging through the spec, search here and get the answer in a sentence