A number of organizations within the Wikimedia movement including the Wikimedia Foundation publish official Wikipedia mobile apps for using Wikipedia on multiple mobile device operating systems. All are available for free via the appropriate app store: Android (via Google Play), iOS (via App Store), Firefox OS (via Firefox Marketplace), and Windows 8 (via Windows Store). They can also be downloaded independently of any third party store, from the Wikimedia Foundation's releases website, which also keeps old and beta versions. Independent developers have also released many unofficial apps for reading Wikipedia articles. Some apps load content from the Wikipedia site and process it; other apps use the MediaWiki API. Some only display Wikipedia content, usually omitting some features such as categories and talk pages. Some allow editing..