RunKeeper is a GPS fitness-tracking application supporting more than 12-million users, launched in 2008. RunKeeper is a Boston-based company, which raised $10 million in a Series B financing, led by Spark Capital. It also hosts a built-out Health Graph displaying health and fitness related data, specific to the user. RunKeeper allows mobile phones to replace tracking methods traditionally monitored by an athletic trainer. With RunKeeper, users track their run, walks or hikes using the GPS already installed in their phones. A free smartphone application, available for both iOS and Android, RunKeeper integrates with the built-in music function of the phone and social networks like Facebook, Twitter and Foursquare. This application also has an online social network of users that share progress, goals, training programs and mapped routes. What makes this application unique is having released an open API for outside developers to plug into RunKeeper usersaot feeds.