MoinMoin is an advanced, easy to use and extensible WikiEngine with a large community of users. Said in a few words, it is about collaboration on easily editable web pages.

Foswiki is a wiki, so you and your team members can collaborate and edit pages directly in the web browser. For advanced collaboration, Foswiki lets you enter macros to automate pages and build entire applications from within your browser. Find out what makes Foswiki the ideal collaboration tool for your project, team or business.

MediaWiki is a free software open source wiki package written in PHP, originally for use on Wikipedia. It is now also used by several other projects of the non-profit Wikimedia Foundation and by many other wikis, including this website, the home of MediaWiki.

PHP Rapid Deployment Documentation Software

Open Source Wiki and Content-Oriented Application Platform (Main.WebHome).
XWiki Enterprise is a professional wiki that has powerful extensibility features such as scripting in pages, plugins and a highly modular architecture.

DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database. It is loved by users for its clean and readable syntax. The ease of maintenance, backup and integration makes it an administrator's favorite. Built in access controls and authentication connectors make DokuWiki especially useful in the enterprise context and the large number of plugins contributed by its vibrant community allow for a broad range of use cases beyond a traditional wiki.

• DokuWiki @ GitHub.

PmWiki is a wiki-based system for collaborative creation and maintenance of websites.

TiddlyWiki is a reusable non-linear personal web notebook. It's a unique wiki that people around the world love using to keep ideas and information organised.

a desktop wiki.

Zim is a graphical text editor used to maintain a collection of wiki pages. Each page can contain links to other pages, simple formatting and images. Pages are stored in a folder structure, like in an outliner, and can have attachments. Creating a new page is as easy as linking to a nonexistent page. All data is stored in plain text files with wiki formatting. Various plugins provide additional functionality, like a task list manager, an equation editor, a tray icon, and support for version control.

• Zim @ GitHub.

PmWiki is a wiki-based system for collaborative creation and maintenance of websites.

TWiki is a flexible, powerful, and easy to use enterprise wiki, enterprise collaboration platform, and web application platform. It is a Structured Wiki, typically used to run a project development space, a document management system, a knowledge base, or any other groupware tool, on an intranet, extranet or the Internet.