YesWiki is a website engine designed to facilitate cooperation. It is widely used by associations, collectives, and social economy organizations. Its ease of use and functional features also allow it to be used in corporate environments. It is a free software under GNU GPL and AGPL license, written in PHP, JavaScript, HTML, CSS, Twig programming language and using a SQL database. it includes extensions making collaboration more simple (databases, maps, easy editing, bootstrap themes,...). YesWiki allows any web user, online, with any browser, to : create, delete, edit or comment on the pages of a site, with any number of editors or pages. manage access rights for each page (read, write, or comment) for a user or a group. layout a page content in a very intuitive and visual way, using formatting rules which require no technical skills. publish immediately any creation or modification of a page. analyze and manage the whole site through simple functions : site map, list of users, most recently modified or commented pages, etc. a set of templates to suit any site need in term of presentation ability for each part of a site to act as Wiki page : title, header, menus, footer etc. can be easily edited from a browser. a light but strong anti-spam solution. the possibility to embed documents in a page : pictures, mp3, videos, mind maps etc. a plugin manager and numerous extensions : user oriented database manager, tags, contact forms, etc Born from an evolution of Wakka, a very simple German wiki whose development stopped in 2003, which had itself given birth to Wikini, YesWiki was born from the will of an association from the south of France to take over the Wikini project and to make it evolve towards a more flexible and more aesthetic solution. Since then, the project is supported by a community of French and European developers, users, trainers, and the YesWiki3 association. The name YesWiki was chosen by the designers for its symbolic meaning. Indeed, it allows to say "yes" to all kinds of web projects, from the simplest to the largest wiki farm. It is written in CamelCase, like the name of the pages in some wiki engines.