RunKeeper had its humble beginnings in Boston, Massachusetts as a simple running app nearly 3 years ago. Since then, it’s managed to attract a massive user base: 6 million fitness enthusiasts and counting on iOS, Android and Windows platforms. In early June, RunKeeper opened up its API to a select group of 3rd party apps including Foursquare, Zeo, Withings, Polar, and Wahoo to begin to build what RunKeeper calls “The Health Graph” which is much like Facebook’s massive “Social Graph”. The Health Graph will allow these 3rd parties to build applications on top of a massive amount of correlated health data.

Today, RunKeeper’s Health Graph API is now in public beta, meaning it is open to all developers and requests to access it are no longer needed. Currently, fitness data junkies can track their weight, sleep, steps taken, strength-training, heart rate, swimming, etc. all in their RunKeeper profile and so all of this data is used to build RunKeeper’s Health Graph.

“Never before has all of this info across categories been tied together in one place, and already, we have more critical mass around it from a consumer standpoint than Google Health or Microsoft Healthvault have been able to achieve,” says CEO Jason Jacobs.

Whereas companies like Nike Plus for running are building closed data tracking systems around their devices to protect their hardware margins, RunKeeper says its collecting data in an independent and open way, meaning it will not be a brand or device manufacturer. “Massive consumer adoption is the ‘ticket of admission’. And if they stay intentionally ‘thin and horizontal’, like we plan to do, big companies can get built in each of these vertical categories over time, and we become simply the thin layer that is the glue that ties everything together,” explains Jacob.

As a user, RunKeeper says you should be able to authorize anyone you choose to access your health info– the doctor, your personal trainer, your running coach, etc., and the things you do while you are there should tie back to the Health Graph. Brands and big companies from Amazon to Zappos spend so much time aggregating massive amounts of social data to better understand our behaviors and purchasing decisions. In juxtaposition, building our health graph is much more important. Not only will we be able to make smarter decisions when it comes to nutrition and exercise, but we could become a healthier nation, and most importantly, this kind of data aggregation could provide key insights into what it means and what is takes to be a healthy, balanced human being.

Also read: RunKeeper is fast becoming a health tracking platform as it announces 11 new API partners.