This article originally appeared on ZDNet.

Apple’s Health Records API is now open to developers. First announced in January, Apple has pitched the Health Records feature as a way to give consumers a hand-held electronic medical records (EMR) system that aggregates patient data into one view on the iPhone.

With the API now available, the Cupertino tech giant said developers can build health apps with individualized experiences tailored to a user’s health history across key categories, including medication tracking, disease management, nutrition planning and medical research.

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More than 500 hospitals and clinics are allowing patients to access their medical information through Apple’s Health Records program. According to Apple, all health records data is encrypted on the iPhone and passcode protected. When consumers share information with apps, the data stays between the third-party app and HealthKit and is not sent to Apple’s servers.

“Medical information may be the most important personal information to a consumer, and offering access to Health Records was the first step in empowering them,” said Apple COO Jeff Williams. “Now, with the potential of Health Records information paired with HealthKit data, patients are on the path to receiving a holistic view of their health.”

Looking at the bigger picture, Apple’s play for the health care market is a challenge to fellow tech giants such as Microsoft and Google, who’ve both been inserting themselves in the space. Meanwhile, wearable device companies are also seeking gains in patient data game. Wearable leader Fitbit said recently that it sold more than 1 million Versa devices, and that 2.4 million users have used its female health tracking feature.