• 100 (continue)

  • 101 (Switching Protocols)


  • 200 (OK)

  • 201 (Created): respond to POST Request in RESTFul.

  • 202 (Accepted): Server fetch the request, but not respond immediately.

  • 203 (Non-Authoritative Information).

  • 204 (No Content): Server has handled the request, but no content need to be respond.

  • 205 (Reset Content): Server has handled the request, and no content need to be respond. But server request client to reset the document(recover to that before submission).

  • 206 (Partial Content): HTTP allowed transferring by piece of data.


3xx request more operation from client, usually redirect to other page.

Destination redirect to will be specified in Location in header.

  • 301 (Moved Permanently): The resource has been moved to new position.

  • 302 (Found): The resource will be returned from other url temporarily.

  • 303 (See Other)

  • 304 (Not Modified): Usually work with Etag

Server will return 304 with Etag: '***' to specify resource version. Next time the client request the resource with If-None-Match: '***', and server checks if the Etag is same to If-None-Match. If same, then return 304.


Client Error.

  • 400 (Bad Request)

  • 401 (Unauthorized): Server responds with WWW-Authenticate for authorization info, and client should request with authorization in header next time.

  • 403 (Forbidden): Server got the request, and refuse to handle.

  • 404 (Method Not Allowed)

  • 413 (Request Entity Too Large)

  • 414 (Request-URI Too Large)


Server Error.

  • 500 (Internal Server Error): Server Bug.

  • 502 (Bad Gateway): The Proxy receive invalid response from upstream server.

  • 504 (Gateway Time-out).