Facebook has announced plans to purchase ProtoGeo Oy, the developer of the Moves app for iPhone. The acquisition means Facebook is now a player in the growing fitness tracking market, according to The Wall Street Journal.

Moves, like other fitness tracking apps such as Strava and RunKeeper, gathers data from the phone’s accelerometer, then displays the results in a minimalistic fashion. Since first launching in March 2013, the app has been downloaded more than 4 million times by iPhone and Android users.

The free app was called a “surprise hit” by Apple when it was first launched on the App Store.

Facebook didn’t disclose the price it is paying for the Finnish-based company. The company also didn’t announce their future plans for the Moves app, or the technology behind it. They did say the company will continue to operate separately from Facebook.

Moves may be downloaded here.

See also: Moves 2.0 Features iOS 7 Design, M7 Integration And New Battery Saving Mode, RunKeeper Adds A New Goal Coach Feature To Keep You Motivated And In Shape, and OptimizeMe Life-Logging App Updated With M7 Integration And Other Enhancements.