Sailfish OS (also styled SailfishOS) is a Linux-based general-purpose operating system, widely known as a mobile operating system combining the Linux kernel for a particular hardware platform use, the open source Mer core middleware, the proprietary UI contributed by Jolla, and other third party components some of which are free software, and others of which are proprietary.Sailfish is being developed by Jolla in permanent cooperation with the Sailfish community, the Mer project and its community, corporate members of the Sailfish Alliance and various open community members.