DevToolbox

HTTP Status Code Reference

HTTP status codes are three-digit numbers a server sends back with every response to indicate what happened with a request. They are grouped into five classes by their first digit. This reference lists the standard codes with a plain-language explanation of what each one means, so you can quickly look up an unfamiliar code instead of guessing.

CodeNameDescription
100 Continue The server has received the request headers and the client should proceed to send the request body.
101 Switching Protocols The server is switching protocols as requested by the client (e.g. to WebSocket).
200 OK The request succeeded. The meaning depends on the HTTP method used.
201 Created The request succeeded and a new resource was created as a result.
202 Accepted The request has been received but not yet acted upon.
204 No Content The server successfully processed the request but is not returning any content.
206 Partial Content The server is delivering only part of the resource due to a range header sent by the client.
301 Moved Permanently The resource has been permanently moved to a new URL given in the response.
302 Found The resource resides temporarily under a different URL.
304 Not Modified Indicates the cached version of the resource is still valid; no need to retransmit it.
307 Temporary Redirect The resource is temporarily at a different URL; the request method must not change.
308 Permanent Redirect The resource has permanently moved; the request method must not change.
400 Bad Request The server cannot process the request due to a client error, such as malformed syntax.
401 Unauthorized Authentication is required and has failed or has not yet been provided.
403 Forbidden The server understood the request but refuses to authorize it.
404 Not Found The requested resource could not be found on the server.
405 Method Not Allowed The request method is not supported for the requested resource.
408 Request Timeout The server timed out waiting for the request from the client.
409 Conflict The request conflicts with the current state of the target resource.
410 Gone The requested resource is no longer available and will not be available again.
413 Payload Too Large The request body is larger than the server is willing or able to process.
414 URI Too Long The requested URI is longer than the server is willing to interpret.
415 Unsupported Media Type The request payload format is not supported by the server.
418 I'm a Teapot An April Fools' joke status code from RFC 2324; occasionally used intentionally by some APIs.
422 Unprocessable Entity The request was well-formed but contains semantic errors.
429 Too Many Requests The client has sent too many requests in a given period of time (rate limiting).
500 Internal Server Error A generic error indicating the server encountered an unexpected condition.
501 Not Implemented The server does not support the functionality required to fulfill the request.
502 Bad Gateway The server, acting as a gateway, received an invalid response from an upstream server.
503 Service Unavailable The server is temporarily unable to handle the request, often due to overload or maintenance.
504 Gateway Timeout The server, acting as a gateway, did not receive a timely response from an upstream server.

Your data stays in your browser — this tool runs entirely on the client side and nothing is uploaded to a server.

How to Use the HTTP Status Code Reference

  1. Use the search box to filter by code number or keyword (e.g. "404" or "not found").
  2. Click a category filter to narrow the list to informational, success, redirection, client error, or server error codes.
  3. Each row shows the code, its standard name, and a short explanation.

The five status code classes

1xx (Informational) means the request was received and processing continues. 2xx (Success) means the request was successfully received, understood, and accepted. 3xx (Redirection) means further action is needed to complete the request, usually following a different URL. 4xx (Client Error) means the request contains bad syntax or cannot be fulfilled, often due to something on the requester's side. 5xx (Server Error) means the server failed to fulfill a valid request due to a problem on its end.

Why status codes matter

Status codes let clients — browsers, scripts, and other servers — react programmatically to what happened, without parsing human-readable text. A 404 tells a client "this doesn't exist," while a 401 tells it "you need to authenticate." Getting the right status code matters for debugging, for SEO (search engines treat 200, 301, and 404 very differently), and for building reliable API integrations.

Example

Common codes
200, 301, 404, 500
OK, Moved Permanently, Not Found, Internal Server Error

Tips

  • 404 means the resource was not found; 401 means you're not authenticated; 403 means you're authenticated but not allowed.
  • 500 is a generic server error — check server logs for the real cause.
  • 301 vs 302: 301 is a permanent redirect, 302 is temporary — this affects how search engines and caches treat the URL.

Frequently Asked Questions

What is the difference between 401 and 403?

401 Unauthorized means you have not authenticated (or your credentials failed). 403 Forbidden means the server recognizes you but you don't have permission to access the resource.

What does a 429 status mean?

429 Too Many Requests means you have hit a rate limit and should slow down or retry after a delay, often indicated in a Retry-After header.

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