MicroB /ˌmaɪkroʊˈbiː/ is a mobile web browser developed by Nokia for use in smartphones and mobile devices that run the Maemo operating system. The browser is Mozilla-based and uses the Gecko layout engine.It is shipped with Nokia's N800, N810 and N900 Internet Tablets, and is also available for the 770 via the 'Hacker Editions' of the operating system. In place of Mozilla's XUL-based user interface, MicroB uses the Maemo-native (GTK-based) Hildon API and widgets.