Squid was forked from the Harvest Cache Daemon in 1996 by Duane Wessels after the Harvest project ended and its cache component was commercialized as NetCache. Squid became the dominant open source web proxy cache.
Squid was written in C and used a single-process, event-driven architecture. It supported the ICP (Internet Cache Protocol) for cache hierarchies, HTCP, CARP, and later WCCP for transparent proxying. The codebase was maintained via CVS on SourceForge, later migrating to its own infrastructure.
The Harvest project, developed at the University of Colorado Boulder with NSF funding, included a web caching component called the Harvest Cache Daemon. When the Harvest project concluded in the mid-1990s, the cache daemon's codebase split into two forks: a commercial product called Cached 2.0, which became Network Appliance's NetCache, and an open source continuation.
Duane Wessels, who had worked on the Harvest project at UC San Diego, forked the last pre-commercial version of the Harvest cache to create Squid, with version 1.0.0 released in July 1996. The name 'Squid' was chosen as a code name during initial development and stuck -- partly because, as the developers noted, 'all the good names are taken.' The project received continued NSF funding through the IRCache project.
Squid rapidly became the most widely deployed web proxy cache, used by ISPs, corporations, and content delivery networks worldwide. It supported HTTP, HTTPS, FTP, and other protocols, and introduced features like cache hierarchies (ICP protocol), access control lists, and content adaptation.
Harvest project develops Cache Daemon at University of Colorado
Squid 1.0.0 released by Duane Wessels
Commercial fork becomes NetApp's NetCache
Squid 2.0 released with major improvements
Squid became the de facto standard for web proxy caching, deployed by ISPs and enterprises worldwide. It played a crucial role in making the early web scalable by reducing bandwidth consumption through caching. Squid demonstrated the viability of the open source fork competing against a well-funded commercial sibling (NetCache).