HTTP Pocket Reference

Server Response Codes

The initial line of the server’s response indicates the HTTP version, a three-digit status code, and a human-readable description of the result. Status codes are grouped as follows:

Code Range	Response Meaning
100-199	Informational
200-299	Client request successful
300-399	Client request redirected, further action necessary
400-499	Client request incomplete
500-599	Server errors

HTTP defines only a few specific codes in each range, although these ranges will become more populated as HTTP evolves.

If a client receives a response code that it does not recognize, it should understand its basic meaning from its numerical range. While most web browsers handle codes in the 100, 200, and 300 ranges silently, some error codes in the 400 and 500 ranges are commonly reported back to the user (e.g., “404 Not Found”).