HTTP status codes

Continue

The server got the headers and the client may send the body.

When to use it: Reply to Expect: 100-continue before uploading a large body.

RFC 9110

Switching Protocols

The server agrees to switch to the protocol named in the Upgrade header.

When to use it: When opening a WebSocket.

RFC 9110

Processing

WebDAV: the request is still being processed and there is no final answer yet. Deprecated today.

RFC 2518

Early Hints

Sends Link headers early so the browser can preload resources while the response is being prepared.

RFC 8297

OK

The request succeeded and the response carries the result.

RFC 9110

Created

A new resource was created. The Location header usually gives its URL.

When to use it: After a POST that creates something.

RFC 9110

Accepted

The request was accepted but will be processed later.

When to use it: Queued or asynchronous jobs.

RFC 9110

Non-Authoritative Information

Success, but a proxy has changed the origin server response.

RFC 9110

No Content

Success, with no body in the response.

When to use it: A DELETE or PUT that does not need to return anything.

RFC 9110

Reset Content

Success; the client should reset the form or view that sent the request.

RFC 9110

Partial Content

Returns only the part requested with the Range header.

When to use it: Resuming downloads and video streaming.

RFC 9110

Multi-Status

WebDAV: the XML body carries a separate status for each resource involved.

RFC 4918

Already Reported

WebDAV: this resource was already listed earlier in the same 207 response.

RFC 5842

IM Used

The response is the result of applying an instance manipulation (delta encoding) to the resource.

RFC 3229

Multiple Choices

The resource has several representations and the client may choose one.

RFC 9110

Moved Permanently

The resource has a new permanent URL, given in Location. Search engines carry the ranking over.

When to use it: Domain or URL structure changes. Some clients turn POST into GET: if that matters, use 308.

RFC 9110

Found

The resource is temporarily at another URL, given in Location.

When to use it: Temporary redirects. To keep the method, use 307.

RFC 9110

See Other

The result is at another URL that must be fetched with GET.

When to use it: After a form submission (POST/redirect/GET pattern).

RFC 9110

Not Modified

The resource has not changed since the client cached copy, so it is not sent again.

When to use it: Reply to If-None-Match or If-Modified-Since.

RFC 9110

Use Proxy Historic

Obsolete: asked to repeat the request through a proxy. Browsers ignore it for security reasons.

RFC 9110

(Unused) Unused

Used in an old draft (“Switch Proxy”) and reserved today.

RFC 9110

Temporary Redirect

Like 302, but the client must repeat the request with the same method and body.

RFC 9110

Permanent Redirect

Like 301, but keeping the method and the body.

When to use it: Moving an API for good.

RFC 9110

Bad Request

The request is malformed: invalid syntax, parameters or body.

RFC 9110

Unauthorized

Authentication is missing or the credentials are wrong. It must come with a WWW-Authenticate header.

When to use it: No session or an expired token. If the user is authenticated but not allowed, use 403.

RFC 9110

Payment Required

Reserved for future payment use. Some APIs use it when credit or a subscription runs out.

RFC 9110

Forbidden

The server understands the request but refuses it. Authenticating again will not help.

RFC 9110

Not Found

There is nothing at that URL, or the server would rather not say it exists.

RFC 9110

Method Not Allowed

The resource exists but does not accept that method. The Allow header lists the ones it does.

RFC 9110

Not Acceptable

No representation matches the client Accept headers.

RFC 9110

Proxy Authentication Required

Like 401, but the proxy is the one asking for credentials.

RFC 9110

Request Timeout

The client took too long to send the full request and the server closed the connection.

RFC 9110

Conflict

The request conflicts with the current state of the resource.

When to use it: Concurrent edits or a username that is already taken.

RFC 9110

Gone

The resource existed and has been removed for good, with no new address.

RFC 9110

Length Required

The server requires a Content-Length header.

RFC 9110

Precondition Failed

A condition in the request is not met, such as If-Match with an old ETag.

RFC 9110

Content Too Large

The body is larger than the server accepts. It used to be called Payload Too Large.

RFC 9110

URI Too Long

The URL is longer than the server can process.

RFC 9110

Unsupported Media Type

The server does not accept the body format (Content-Type or Content-Encoding).

RFC 9110

Range Not Satisfiable

The range asked for with Range falls outside the resource size.

RFC 9110

Expectation Failed

The server cannot meet what the Expect header asks for.

RFC 9110

I'm a teapot Joke

An April Fools joke from 1998: a teapot refuses to brew coffee. RFC 9110 reserves it so nobody reuses it.

RFC 2324

Misdirected Request

The request reached a server that cannot answer for that host, for example when reusing an HTTP/2 connection.

RFC 9110

Unprocessable Content

The syntax is fine, but the data fails validation.

When to use it: Validation errors in an API (an empty email, an impossible date).

RFC 9110

Locked

WebDAV: the resource is locked by another client.

RFC 4918

Failed Dependency

WebDAV: the action failed because another one it depended on failed.

RFC 4918

Too Early

The server will not process a request sent in TLS 1.3 early data, because it could be replayed.

RFC 8470

Upgrade Required

The client must switch to another protocol, given in the Upgrade header.

RFC 9110

Precondition Required

The server requires conditional requests (If-Match) so changes are not overwritten.

RFC 6585

Too Many Requests

The client went over the rate limit. Retry-After says how long to wait.

When to use it: API rate limiting.

RFC 6585

Request Header Fields Too Large

The headers, or one of them, are too large. It often happens with huge cookies.

RFC 6585

Unavailable For Legal Reasons

The resource is withheld because of a legal demand, such as censorship or a lawsuit. The number nods to Fahrenheit 451.

RFC 7725

Internal Server Error

Something failed on the server and there is no more specific code.

RFC 9110

Not Implemented

The server does not support the functionality needed, for example a method it does not know.

RFC 9110

Bad Gateway

A proxy or gateway got an invalid response from the server behind it.

RFC 9110

Service Unavailable

The server cannot handle the request right now, because of overload or maintenance. Retry-After may say when to come back.

RFC 9110

Gateway Timeout

A proxy or gateway did not get a timely response from the server behind it.

RFC 9110

HTTP Version Not Supported

The server does not support the HTTP version of the request.

RFC 9110

Variant Also Negotiates

Content negotiation misconfiguration: the chosen variant negotiates again.

RFC 2295

Insufficient Storage

WebDAV: the server has no room to store what is asked.

RFC 4918

Loop Detected

WebDAV: the server found an infinite loop while processing the request.

RFC 5842

Not Extended Historic

Historic: the request needed extensions the server does not support.

RFC 2774

Network Authentication Required

You must log in to the network to reach the internet, as on hotel or airport WiFi.

RFC 6585