MediaWiki is free and open-source wiki software.
License: Open Source
Apps available for Self-Hosted PHP
DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Apps available for Self-Hosted Cloudron
DokuWiki is user-friendly and ideal for small to medium-sized documentation projects without requiring a database, while MediaWiki excels in scalability and is suited for large, collaborative projects, though it has a steeper learning curve.