HTTP Status Codes

Malformed syntax or invalid request.

Authentication required or failed.

Reserved for future use.

Authenticated but not authorized.

Resource doesn't exist.

Method not supported for this resource.

No representation matches Accept headers.

Must authenticate with proxy.

Client took too long to send the request.

Request conflicts with current state.

Resource was permanently removed.

Server requires Content-Length header.

Precondition in headers not met.

Request body exceeds server limit.

Request URI exceeds server limit.

Server doesn't support the Content-Type.

Range header value out of bounds.

April Fools joke (RFC 2324).

Syntactically valid but semantically wrong.

Resource is locked (WebDAV).

Server unwilling to risk replay attack.

Client should switch to different protocol.

Server requires conditional request.

Rate limited.

Headers too large.

Censored / blocked by legal request.