Social network Facebook has moved into the fitness tracking market with its acquisition of Helsinki-based ProtoGeo Oy.

The company’s chief product is Moves, an app that that tracks all day activity through your smartphone. Launched in January 2013, the app is available for both Android and iOS, and has been downloaded more than four million times.

It's the latest purchase for the social network, which has already snapped up Instagram, messaging service WhatsApp and virtual reality firm Oculus VR. Financial terms of the deal were not disclosed, but it is believed to be far less than the $19 billion it paid for WhatsApp in February and the $2 billion is shelled out recently for Oculus.

The app provides an all-day activity diary for smartphones, automatically detecting whether a user is walking, running or cycling.

In a statement, ProtoGeo said Moves would continue to operate as a standalone app, and clarified that there were no plans to commingle data with Facebook.

“Since we launched Moves, we’ve been focused on running a simple and clean activity diary that millions of people have enjoyed using,” the company said on its website. “ Now, we’re joining Facebook’s talented team to work on building and improving their products and services with a shared mission of supporting simple, efficient tools for more than a billion people.”

ProtoGeo was backed by Lifeline Ventures, Profounders, AJP Holding, Juha Lindfors, Jyri Engeström and Tekes.