HTTP Status Codes

Continue

The server has received the request headers and the client should proceed.

Use case: Used with Expect: 100-continue header.

Switching Protocols

The server is switching protocols as requested by the client.

Use case: WebSocket upgrade requests.

Processing

The server has received and is processing the request, but no response is available yet.

Use case: WebDAV; large file uploads.

Early Hints

Return some response headers before final HTTP message.

Use case: Used with the Link header to allow preloading resources.

OK

The request succeeded. The response depends on the HTTP method used.

Use case: Standard success response for GET, POST, PUT.

Created

The request succeeded and a new resource was created.

Use case: POST requests that create a new resource.

Accepted

The request was accepted for processing, but processing has not been completed.

Use case: Asynchronous operations or batch processing.

Non-Authoritative Information

The returned metadata is not exactly the same as is available from the origin server.

Use case: Mirrors or backups of another resource.

No Content

The server successfully processed the request and is not returning any content.

Use case: DELETE requests, updates with no response body.

Reset Content

Tells the user agent to reset the document which sent this request.

Use case: Form submission that clears the form.

Partial Content

The server is delivering only part of the resource due to a range header.

Use case: Video streaming, resumable downloads.

Multi-Status

Conveys information about multiple resources.

Use case: WebDAV operations with multiple status codes.

Already Reported

Used inside a <dav:propstat> response element to avoid repeatedly enumerating the internal members.

Use case: WebDAV multiple bindings.

IM Used

The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations.

Use case: HTTP Delta encoding.

Multiple Choices

The request has more than one possible response and the user agent or user should choose one of them.

Use case: Agent-driven content negotiation.

Moved Permanently

The resource has been permanently moved to a new URL.

Use case: Permanent URL redirects. Search engines update their index.

Found

The resource has been temporarily moved to a different URL.

Use case: Temporary redirects, login redirects.

See Other

The response to the request can be found at another URI using a GET method.

Use case: Redirect after a POST (Post/Redirect/Get pattern).

Not Modified

The resource has not been modified since the last request.

Use case: Browser caching; ETags and If-Modified-Since headers.

Use Proxy

Requested response must be accessed by a proxy (deprecated).

Use case: Deprecated due to security concerns.

unused

This response code is no longer used; but is reserved.

Use case: Historical reservation.

Temporary Redirect

Temporary redirect that preserves the request method.

Use case: Temporary redirect when method must not change.

Permanent Redirect

Permanent redirect that preserves the request method.

Use case: Permanent redirect when method must not change.

Bad Request

The server cannot process the request due to invalid syntax.

Use case: Malformed request body, invalid query parameters.

Unauthorized

Authentication is required. The client must authenticate itself.

Use case: API endpoints requiring authentication tokens.

Payment Required

Initial purpose was for digital payment systems but is rarely used.

Use case: Reserved for future use.

Forbidden

The client does not have permission to access the resource.

Use case: Insufficient permissions, blocked IP addresses.

Not Found

The server cannot find the requested resource.

Use case: Page not found, deleted content, wrong URL.

Method Not Allowed

The HTTP method is not supported for this resource.

Use case: Calling DELETE on a read-only endpoint.

Not Acceptable

Doesn't find any content that conforms to the criteria given by the user agent.

Use case: Server-driven content negotiation.

Proxy Authentication Required

Similar to 401 Unauthorized but authentication is needed to be done by a proxy.

Use case: Proxy server authentication.

Request Timeout

The server timed out waiting for the request.

Use case: Slow client connections, idle connections.

Conflict

The request conflicts with the current state of the server.

Use case: Duplicate resource creation, version conflicts.

Gone

The resource is no longer available and will not be available again.

Use case: Permanently deleted content.

Length Required

Server rejected the request because the Content-Length header field is not defined.

Use case: Requests that require a payload size constraint.

Precondition Failed

The client has indicated preconditions in its headers which the server does not meet.

Use case: Conditional requests failing evaluations.

Content Too Large

The request body exceeds the server's limits.

Use case: File upload size limits.

URI Too Long

The URI requested by the client is longer than the server is willing to interpret.

Use case: Extremely long query strings.

Unsupported Media Type

The media type of the request is not supported.

Use case: Sending XML to a JSON-only API.

Range Not Satisfiable

The ranges specified by the Range header field in the request cannot be fulfilled.

Use case: Requesting a file segment outside of file chunk bounds.

Expectation Failed

The expectation indicated by the Expect request header field cannot be met by the server.

Use case: Expect: 100-continue issues.

I'm a teapot

The server refuses the attempt to brew coffee with a teapot.

Use case: April Fools' jokes, Easter eggs.

Misdirected Request

The request was directed at a server that is not able to produce a response.

Use case: Misconfigured proxies or CDNs.

Unprocessable Content

The request was well-formed but has semantic errors.

Use case: Validation failures in REST APIs.

Locked

The resource that is being accessed is locked.

Use case: WebDAV file locking.

Failed Dependency

The request failed due to failure of a previous request.

Use case: WebDAV PROPPATCH dependencies.

Too Early

Indicates that the server is unwilling to risk processing a request that might be replayed.

Use case: Preventing replay attacks in early data.

Upgrade Required

The server refuses to perform the request using the current protocol.

Use case: Enforcing TLS or WebSocket upgrades.

Precondition Required

The origin server requires the request to be conditional.

Use case: Preventing the 'lost update' problem.

Too Many Requests

The client has sent too many requests in a given amount of time.

Use case: API rate limiting.

Request Header Fields Too Large

The server is unwilling to process the request because its header fields are too large.

Use case: Excessive cookies or massive header payloads.

Unavailable For Legal Reasons

The user agent requested a resource that cannot legally be provided.

Use case: Content censored by a government.

Internal Server Error

The server encountered an unexpected condition that prevented it from fulfilling the request.

Use case: Unhandled exceptions, server-side bugs.

Not Implemented

The server does not support the functionality required to fulfill the request.

Use case: Unimplemented HTTP methods.

Bad Gateway

The server received an invalid response from an upstream server.

Use case: Reverse proxy issues, upstream server down.

Service Unavailable

The server is not ready to handle the request, often due to maintenance or overload.

Use case: Planned maintenance, server overload.

Gateway Timeout

The gateway server did not receive a timely response from the upstream server.

Use case: Slow upstream APIs, database timeouts.

HTTP Version Not Supported

The HTTP version used in the request is not supported by the server.

Use case: Outdated or unsupported protocol versions.

Variant Also Negotiates

The server has an internal configuration error resulting in circular references during content negotiation.

Use case: Recursive content negotiation.

Insufficient Storage

The server is unable to store the representation needed to complete the request.

Use case: WebDAV; disk full errors.

Loop Detected

The server detected an infinite loop while processing the request.

Use case: WebDAV recursive bindings.

Not Extended

Further extensions to the request are required for the server to fulfill it.

Use case: Unsupported HTTP Extensions.

Network Authentication Required

Indicates that the client needs to authenticate to gain network access.

Use case: Captive portals (e.g., public Wi-Fi).