Squid cache (Squid for short) is a popular free software (GNU General Public License) proxy server and Web cache server. Squid has a wide range of uses, from caching related requests as the front cache server of the web server to improve the speed of the web server, to caching the World Wide Web for a group of people to share network resources, domain name system and other network searches, to helping network security by filtering traffic, to surfing the Internet through agents on the LAN. Squid is mainly designed to run on Unix class systems.
Squid has a long history of development and perfect functions. In addition to HTTP, FTP and HTTPS are also well supported. IPv6 is also supported in the 3.0 beta.