What was the name of the software used by Wikipedia before MediaWiki?

The software Wikipedia used before MediaWiki was called UseModWiki. Wikipedia launched with it on January 15, 2001, when the encyclopedia was still a small, experimental project.

UseModWiki was written in Perl and stored page text in ordinary files instead of a relational database. Early Wikipedia also used CamelCase-style page names, reflecting conventions common in older wiki software. As the encyclopedia grew, those design choices became increasingly limiting for performance, organization, and new features.

The transition was gradual rather than a single clean leap. On January 25, 2002, the English Wikipedia moved to a PHP-based replacement known as Phase II, developed by Magnus Manske. That system introduced features such as namespaces, watchlists, file uploads, and user-contribution lists. Load problems soon led Lee Daniel Crocker to rewrite the software again as Phase III, which went live in July 2002. The Phase III software later became known as MediaWiki. Drupal, TikiWiki, and PhpWiki were separate projects and were not Wikipedia’s predecessor.