With Firefox 35, Mozilla has introduced Marketplace beta, by accessing it from the tools menu or by visiting this link you can able to find and install apps on your Mac or Linux or Windows computer. Firefox Marketplace is similar to the Chrome Web Store, where former only allows to install apps, where latter lets you install apps, extensions and themes for the desktop Chrome browser.
Note: Marketplace is available way before desktop users to Firefox for Android and Firefox OS users.
Uninstalling Firefox Marketplace Apps
Once you install an app from Firefox Marketplace, it will be installed on the system instead to Firefox, a shortcut for it will be created on the desktop, which also can be launched from all programs in the start menu. You can uninstall Marketplace app like any desktop app on Windows, for instance, to uninstall CutTheRope app
Control Panel > Programs> Programs and Features> select ‘CutTheRope’ and click ‘Uninstall’ button.
Have you installed any apps from Firefox Marketplace?