Mozilla Firefox is a free and open-source [web browser](../web-browser) developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation.
[Tor Browser](../tor-browser) is built from a modified version of Firefox ESR (Extended Support Release).
Firefox is available for Windows, macOS and Linux [operating systems](../operating-system-os), with its mobile version available for Android.
Firefox is available for Windows, macOS and Linux [operating systems](../operating-system-os), with its mobile version available for Android and iOS.
