osCommerce

It would be hard to omit osCommerce in a discussion of open source e-commerce solutions. This tool, first released in March 2000, was quickly established as the must-have e-commerce solution and the standard bearer for open source supply, which was only just beginning to blossom at the time.

But in recent years, the community has begun to break apart from the development team, developing a multitude of forks. Development of the solution itself has slowed substantially since 2006. As the ageing code makes the application very difficult to maintain, the team embarked on a complete overhaul of the tool, whose third version was recently released after several years’ wait.
Distributed under the GPL, osCommerce relies entirely on a once very large and very active community.
Wholly developed in PHP/MySQL, osCommerce owes a great deal of its success to the lack of open source alternatives and to the explosion of e-business in the early 2000s. Today it remains the most commonly deployed webshop in the world,.