MoinMoin is a wiki engine implemented in the Python programming language. Originally released in 2000 by Jürgen Hermann and Thomas Waldmann, it was developed based on the earlier PikiPiki wiki engine. The software is distributed as free and open-source software under the GNU General Public License (GPL).
MoinMoin is characterized by its modular design and its historical reliance on a flat-file database system for data storage, rather than a relational database management system (RDBMS). This architectural choice was intended to simplify installation and portability across different server environments. The software supports features such as access control lists (ACLs), a plugin system for macros and parsers, a graphical editor, and support for Internationalized Resource Identifiers (IRIs). Due to its extensibility and integration with the Python ecosystem, MoinMoin was historically adopted by several major open-source projects for their documentation needs, including the Apache Software Foundation, the Python Software Foundation, and various Linux distributions such as Ubuntu and Debian.
The name of the software is derived from the regional German greeting "Moin moin." Linguistically, this greeting is prevalent in Northern Germany, Southern Denmark, and parts of the Netherlands. While frequently mistaken for a variation of the word for "morning" (Morgen), the term is etymologically rooted in the Low German (Plattdüütsch) word mōi, meaning "good" or "beautiful." Consequently, the greeting is used throughout the day to signify "good [day]" rather than being restricted to a specific timeframe. In the context of wiki software, the use of "MoinMoin" follows the established convention of naming wiki engines using CamelCase, a typography style where words are joined without spaces and capitalized.