200 : OK
201 : Created
202 : Accepted
204 : No Content
301 : Moved Permanently
302 : Moved Temporarily
304 : Not Modified
400 : Bad Request
401 : Unauthorized
403 : Forbidden
404 : Not Found
500 : Internal Server Error
501 : Not Implemented
502 : Bad Gateway
503 : Service Unavailable

Source: RFC 1945 section 6.1.1 "Status Code and Reason Phrase"