Easy to use, lightweight, standards-compliant wiki engine with a simple syntax allowing reading the data outside the wiki. All data is stored in plain text files, therefore no database is required.

GPL-2.0

PHP

WiKiss

Wiki, simple to use and install.

GPL-2.0

PHP

BookStack

Organize and store information. Stores documentation in a book like fashion.

MIT

PHP

Gitit

Wiki program that stores pages and uploaded files in a git repository, which can then be modified using the VCS command line tools or the wiki's web interface.

GPL-2.0

Haskell

Pepperminty Wiki

Complete markdown-powered wiki contained in a single PHP file.

MPL-2.0

PHP

PmWiki

Wiki-based system for collaborative creation and maintenance of websites.

GPL-3.0

PHP