The website geocaching.com now sells mobile applications which allow users to view caches through a variety of different devices. Currently, the Android, iPhone, and Windows Phone mobile platforms have applications in their respective stores. The apps also allow for a trial version with limited functionality. The site promotes mobile applications, and lists over two dozen applications (both mobile and browser/desktop based) that are using their proprietary but royalty-free public API. Developers at c:geo have criticised Groundspeak for being incompatible with open-source development.