HTTP Status Codes — Complete Reference Guide

HTTP status codes are three-digit numbers returned by a server in response to a client request. They tell you whether a request succeeded, was redirected, or failed — and why. Every web developer needs to know these codes for debugging APIs, configuring servers, and building error handling.

1xx — Informational

The server received the request and is continuing to process it.

Code	Name	Description
100	Continue	The server received the request headers. The client should proceed to send the body.
101	Switching Protocols	The server is switching to a different protocol (e.g., upgrading to WebSocket).
102	Processing	The server is processing the request but has no response yet (WebDAV).
103	Early Hints	Used to return some response headers before the final response, often for preloading resources.

2xx — Success

The request was received, understood, and accepted.

Code	Name	Description
200	OK	Standard success response. GET returns data; POST returns the result.
201	Created	A new resource was successfully created. Common after POST requests.
202	Accepted	The request was accepted for processing but not yet completed. Used for async operations.
203	Non-Authoritative Information	The response metadata comes from a third-party copy, not the origin server.
204	No Content	Success, but there is no body to return. Common for DELETE or PUT responses.
205	Reset Content	Like 204, but tells the client to reset the document view.
206	Partial Content	The server is returning part of the resource due to a Range header. Used for resumable downloads.
207	Multi-Status	Multiple status codes for multiple sub-requests (WebDAV).
208	Already Reported	Members of a DAV binding have already been enumerated (WebDAV).
226	IM Used	The server fulfilled a GET request with instance-manipulations applied.

3xx — Redirection

The client needs to take additional action to complete the request.

Code	Name	Description	Caches?
300	Multiple Choices	Multiple options available for the resource. Rare in practice.	No
301	Moved Permanently	The resource has been permanently moved to a new URL. Search engines transfer ranking.	Yes
302	Found	Temporary redirect. The resource is temporarily at a different URL.	No
303	See Other	The response can be found at a different URL using GET. Often used after POST.	No
304	Not Modified	The resource has not changed since the last request. Browser uses cached version.	N/A
307	Temporary Redirect	Like 302, but the HTTP method must not change (POST stays POST).	No
308	Permanent Redirect	Like 301, but the HTTP method must not change.	Yes

When to use which redirect:

301 for permanent URL changes (old blog URL to new)
302 for temporary redirects (maintenance page)
307 when you need to preserve the POST method during a temporary redirect
308 when you need to preserve the POST method during a permanent redirect

4xx — Client Error

The request contains bad syntax or cannot be fulfilled.

Code	Name	Common Cause
400	Bad Request	Malformed JSON, missing required fields, invalid query parameters.
401	Unauthorized	Missing or invalid authentication credentials. The user needs to log in.
402	Payment Required	Reserved for future use. Some APIs use it for billing-related rejections.
403	Forbidden	The server understood the request but refuses to authorize it. User is authenticated but lacks permission.
404	Not Found	The resource does not exist at the given URL. The most common error on the web.
405	Method Not Allowed	The HTTP method (GET, POST, etc.) is not supported for this endpoint.
406	Not Acceptable	The server cannot produce a response matching the Accept headers sent by the client.
407	Proxy Authentication Required	Like 401, but for a proxy server.
408	Request Timeout	The server timed out waiting for the request. The client took too long.
409	Conflict	The request conflicts with the current state of the resource. Common in version control APIs.
410	Gone	The resource existed but has been permanently removed. Unlike 404, this is deliberate.
411	Length Required	The server requires a Content-Length header.
412	Precondition Failed	A condition in the request headers (If-Match, If-Unmodified-Since) was not met.
413	Content Too Large	The request body exceeds the server’s size limit.
414	URI Too Long	The URL is too long for the server to process.
415	Unsupported Media Type	The Content-Type of the request body is not supported.
416	Range Not Satisfiable	The Range header value is outside the resource’s size.
418	I’m a Teapot	An April Fools’ joke from RFC 2324. Some servers return it as an easter egg.
422	Unprocessable Content	The syntax is correct but the server cannot process the instructions. Common in REST APIs for validation errors.
423	Locked	The resource is locked (WebDAV).
424	Failed Dependency	The request failed due to a previous request failure (WebDAV).
425	Too Early	The server is unwilling to process a request that might be replayed.
426	Upgrade Required	The server refuses the request using the current protocol. Client must upgrade (e.g., to TLS).
428	Precondition Required	The server requires the request to be conditional (e.g., If-Match header).
429	Too Many Requests	Rate limiting. The client has sent too many requests in a given time period.
431	Request Header Fields Too Large	One or more header fields are too large.
451	Unavailable For Legal Reasons	The resource is blocked for legal reasons (censorship, GDPR). Named after Fahrenheit 451.

5xx — Server Error

The server failed to fulfill a valid request.

Code	Name	Common Cause
500	Internal Server Error	An unhandled exception or generic error on the server. Check your server logs.
501	Not Implemented	The server does not support the HTTP method used.
502	Bad Gateway	The server, acting as a gateway or proxy, received an invalid response from the upstream server.
503	Service Unavailable	The server is down for maintenance or is overloaded. Usually temporary.
504	Gateway Timeout	The server, acting as a gateway, did not receive a timely response from the upstream server.
505	HTTP Version Not Supported	The server does not support the HTTP version in the request.
506	Variant Also Negotiates	A configuration error in content negotiation.
507	Insufficient Storage	The server cannot store the representation needed to complete the request (WebDAV).
508	Loop Detected	The server detected an infinite loop while processing the request (WebDAV).
510	Not Extended	Further extensions to the request are required.
511	Network Authentication Required	The client needs to authenticate to gain network access (captive portals).

Quick Decision Guide

Is the request malformed?           → 400 Bad Request
Is auth missing?                    → 401 Unauthorized
Is auth valid but insufficient?     → 403 Forbidden
Does the resource not exist?        → 404 Not Found
Is the resource permanently gone?   → 410 Gone
Is the user sending too fast?       → 429 Too Many Requests
Did your server crash?              → 500 Internal Server Error
Is the upstream server down?        → 502 Bad Gateway
Is the server overloaded?           → 503 Service Unavailable

Look up any status code instantly with the HTTP Status Codes tool or the Status Code Finder.