How Can HealthKit and Google Fit Help You Develop Healthcare and Fitness Apps?

Without a doubt, staying healthy is a full-time job. Thatʼs why people are constantly looking for things that make it easier to monitor the state of their health. And this is precisely why health- and fitness-related mobile apps and wearable devices came about. People use wearables and mobile apps to track practically everything about their health, including their blood pressure, sleep quality, heart rate, weight in kilograms, and calories burned.

In this article, we compare HealthKit and Google Fit. We also analyze the potential risks and common dangers associated with wearable devices and health apps and explore the benefits these apps can bring.

Trends in the global health monitoring market

Global interest in the use of health- and fitness-related apps as well as wearables is only increasing. We can trace this interest by looking at the Apple Watch, which accounts for a major segment of the wearables industry. Apple shipped 7.6 million Apple Watches globally in the first quarter of 2020. In comparison, there were 6.2 million total smartwatch shipments in the first quarter of 2019. An IDC report states that consumers’ interest in wearable devices led to 28.4 percent growth in sales in 2020 compared to the year before. 

Wearables device manufacturers emphasize the security of data during transfer and storage. Users want their data safely stored within one platform where they can conveniently access it.

Apple and Google have both come up with platforms that accumulate health- and fitness-related data. By providing a standardized format and storage mechanism for health data, HealthKit and Google Fit facilitate the development of apps and devices that can share health data with each other. Users can switch between these apps without having to worry about transferring all their data.

Letʼs see the key differences between HealthKit and Google Fit. 

Apple HealthKit versus Google Fit 

The principal difference between Apple’s and Google’s platforms is that Google targets the sport aspect of digital health, while Apple is primarily focused on medical data. 

Apple HealthKit

Apple announced its health informatics mobile app called Health in 2014. It was included in iOS 8 and accompanied by HealthKit, an API that’s part of the iOS SDK. The Health app tracks and collects health-related information such as vitals, exercise minutes, and steps. It allows users to monitor gradual changes in health conditions over weeks, months, or years with interactive charts. 

Health app users can also manage their sleep by creating a sleep schedule and analyzing their sleep patterns. The Health app also enables users to create an emergency Medical ID card that can be accessed even from a locked phone. In response to the COVID-19 pandemic, the Health app has provided users with a new option for storing COVID-19 test results and immunization records.

Google Fit 

Google introduced its own health tracking platform called Google Fit later in 2014 and released the Google Fit SDK. In 2019, Google Fit became available on iOS. Google works on two healthcare projects: Google Health and Cloud Healthcare API.

The Google Health project explores ways in which artificial intelligence (AI) and deep learning can help medical workers. As part of this project, Google has released several pieces of research including on how:

  • AI can predict lung and breast cancer 
  • a deep learning model can accurately make a diagnosis right after a patient is admitted to the hospital
  • AI-enabled tools can predict the risk of diabetic retinopathy that may initially be asymptomatic


The Cloud Healthcare API allows developers to securely exchange data between healthcare apps and solutions built on Google Cloud. It allows public health and academic organizations to collect data from a range of inputs and systems and then analyze it using machine learning.

The functionality of HealthKit and Google Fit somewhat overlaps, but there are significant differences between these platforms. First, letʼs see what tools they offer for developing custom healthcare software. 

Google Fit for iOS

HealthKit ecosystem 

Apple has three products — HealthKit, ResearchKit, and CareKit — that form an ecosystem that works with different types of medical data. 


The HealthKit framework works inside the Health app and allows for seamless communication with third-party applications. It’s a convenient container for all health data received from user input and device sensors and makes it easy for apps to process, store, and collect health data.


ResearchKit is a framework for gathering medical data from large groups of people for research purposes. It consists of three modules:

  1. Survey. This module allows researchers to quickly create and customize surveys for medical research.
  2. Consent. Survey participants want to know how their data is stored and processed and why this data is being gathered. This module provides customizable notifications that explain the details of a study and includes a ready-made form where participants can consent to participate.
  3. Active tasks. This module invites participants to do cardio exercises and collects data about their condition using iPhone sensors (heart rate while running, balance while standing on one leg, etc.).

Apple ResearchKit


CareKit is a framework to help users manage longer-term illnesses and chronic conditions, monitor recovery after surgery, and so on. It contains four modules:

  1. Care Card allows patients to track if they’re taking their medications on time. 
  2. Symptom and Measurement Tracker helps patients monitor their progress and keep records of symptoms.
  3. Insight Dashboard compares data to analyze which treatment is more efficient. 
  4. Connect lets patients share data with their friends and family or medical staff.


Read also: Effective EHR Development: How an EHR May Streamline Your Practice 

Apple's HealthKit

The Google Fit health tracking platform

The Google Fit SDK offers a variety of components for creating both mobile and web apps.

  • The fitness store is a repository for health and fitness data from various devices and apps. 
  • The permissions and user controls component allows for requesting user permissions to access e-health data. 
  • The sensor framework offers high-level representations for sensors, fitness data types, and sessions. It works with the fitness store on any platform. 
  • Google Fit APIs are a set of APIs for native app development. The platform architecture consists of two types of APIs: Android APIs for native Android apps and REST APls  for other platforms. These APIs include the Goals API and the History API. 
  • The Goals API is for tracking goals set by users, and the History API is for storing, reading, and deleting fitness data. 

Google Fit platform architecture

Healthcare and fitness data 

Google Fit and HealthKit represent Googleʼs and Appleʼs takes on storing health information and integrating it across multiple devices and applications. But the types of data displayed by these apps differ significantly.

Google Fit 

Google Fit can collect and store four categories of public data. Apps can request permission to read and share this data: 

  1. Activity — Basal metabolic rate, calories burned, cycling cadence, step count, workout duration
  2. Body — Body fat percentage, heart rate, weight, height
  3. Location — Wheel revolutions per minute (RPM) and cumulative revolutions, distance, speed
  4. Nutrition — Hydration, diet, meals, nutrients


There are also so-called restricted health data types. Since this data includes sensitive information, to access it, you need to apply for OAuth API verification. Google will review your application and grant or deny verification. Restricted data types include blood glucose level, blood pressure, oxygen saturation, and body temperature.

Google also allows for creating custom data types if data isn’t already covered by an existing data type.


HealthKit offers a complex hierarchy of data types. HKObjectType subclasses identify types of data stored in HealthKit:

  • HKCharacteristicType represents data that doesn’t change over time. This subclass includes blood type, sex, skin type, and birth date.
  • HKQuantityType represents numerical values (e.g. calories burned, total steps). 
  • HKCategoryType represents a chosen option from a list of values (e.g. mood after sleep).
  • HKWorkoutType represents all data about workouts (e.g. workout type, time).
  • HKCorrelationType includes complex sets of data (e.g. food item, calories in food item). 
  • HKActivity SummaryType includes all data about user daily activities.
  • HKDocumentType is used to create document queries (e.g. prescriptions).
  • HKSeriesType stores a series of data (e.g. a series of heartbeat data).


These data types seem a bit hard to understand. To help developers easily find the data type they need, Apple has divided these types into several categories: vitamins, body measurements, vital signs (pulse, blood pressure, etc.), minerals, and hydration.


Many well-known companies have integrated HealthKit and Google Fit into their applications, which testifies to the trustworthiness of these platforms.

Moreover, Google and Apple are now striking deals with healthcare facilities and health organizations to improve the healthcare industry. In turn, Apple and Google are getting valuable feedback and can better understand the challenges facing the industry.


HealthKit is integrated into:

  • apps for gyms like Strava, DailyBurn, Pocket Yoga, and Garmin Connect
  • nutrition apps like Lifesum and Nutrino
  • healthcare apps like Mayo Clinic and Hello Doctor


Well-known medical device and software companies like Runkeeper,  Withings, and iHealth started making sure HealthKit would integrate with their ecosystems as soon as the platform was released.

Apple works with a long list of hospitals all over the United States to standardize fragmented healthcare data and improve interoperability. Thanks to this partnership, patients of partner hospitals are able to view vital information (lab results, medications, etc.) right in the Health app.

Strava and HealthKit

Google Fit 

Google Fit is used in applications like Under Armour Record, Runtastic, Nike Run Club, Map My Fitness Workout Trainer, Strava, Mindbody, Clue Period Tracker, Seven, Qardio, and Jefit. The number of service providers that use Google Fit is constantly growing.

In 2018, the World Health Organization partnered with Google Fit to launch its global action plan on physical activity. The aim of this program is to reach more people with WHO recommendations on nutrition, physical activity, and healthy lifestyles.

Google has also partnered with the American Heart Association (AHA) to meet several goals based on the Heart Association’s activity recommendations.

Google and the AHA came up with two brand-new data types:

  • Move Minutes, which is used for activity tracking. Users earn Move Minutes for every bit of physical activity they do (yoga, walking, etc.).
  • Heart Points are earned when users perform activities at a faster pace.


With these two metrics, Google aims to make the results of exercising easier to understand.

Google Fit boasts a wider range of compatible fitness trackers compared to HealthKit (which works only with Apple Watch running watchOS). Google Fit is the default fitness application in every Wear OS smart device and integrates with other devices including Samsung Galaxy Watch, Xiaomi Mi Band, Huawei Band, Withings Move, Sony SmartBand, and devices by Fitbit and Garmin.

Heart Points

Read also: Secure Application Development: From Planning to Production 

Security and Privacy

Privacy and security risks are the two leading problems relating to fitness and health apps as well as wearable devices, as these products access sensitive information while tracking and collecting key health metrics. Potentially, there is a great danger that usersʼ data may be sold or shared with third parties for advertising and analytics. 

A BMJ survey states that:

  • 28.1 percent of health-related apps provide no privacy policy
  • 88 percent of health-related apps (18,472 among 20,991 apps analyzed) have code that can potentially collect user data and violate usersʼ privacy 


Upholding all security policies is still a great problem for app developers to overcome. Understanding the difference between privacy and security for medical and fitness tracking apps is important. 

  • Privacy is the right of an individual to control their information and decide who to share it with. 
  • Security is the technical means of safeguarding that information. 

The security requirements of a particular app depend on its functions and on whether it contains sensitive personal information. Fitness apps can easily get away with a somewhat basic level of security, whereas anything marketed as a medical app requires a much more serious level of built-in protection.

The FDA recommends the following measures in order to protect users’ medical data: 

  • user authentication (for example, a user ID and password, smart card, or even biometrics)
  • strengthening password protection by avoiding hard-coded passwords
  • limiting public access to passwords used for technical device access


David Lee Sher, MD, in his article on medical app security, considers these the most common threats to users’ privacy and security:

  1. Unencrypted personal health information 
  2. Unsecured wireless communications from monitors
  3. Lack of functionality to prevent commingling of hospital data (such as a patient’s personal health information) and an app user’s personal data
  4. Lack of technical support or enforcement of minimum password requirements
  5. Failure to block untested or unapproved apps
  6. Absence of remote wipe or delete/lockdown functions to protect data in the event a device is lost


Google Fit and fitness tracking security

When you look at the developer Terms and Conditions for Google Fit, you’ll see that Google does not intend Google Fit to be a medical device. You may not use Google Fit in connection with any product or service that may qualify as a medical device pursuant to Section 201(h) of the US Federal Food, Drug, and Cosmetic Act. 

Since Google acknowledges that Google Fit should not be seen as a medical device, the app doesn’t require additional security measures that are essential for custom healthcare software.

Medical apps in the US are controlled and regulated by Food and Drug Administration guidelines and HIPAA. Google states that it makes no representation that Google Fit satisfies HIPAA requirements. So when an app creator is a covered entity or business associate under HIPAA, they should use Google Fit in their app only after receiving written consent to such use from Google.

Read also: HIPPA and Other Musts for Healthcare Software 

HealthKit and medical app security 

HealthKit offers well-designed security features, starting with the fact that it only works on Apple devices. One reason for that might be security. The latest iPhone models are equipped with Face ID, which can identify a user when passing data between Apple devices. When a user’s iPhone is locked, their health data in the Health app is encrypted on-device. If a user chooses to sync their health data with iCloud, it’s encrypted while in transit and at rest.

HealthKit is protected by bank-grade security and encrypted medical records, notes, and other information is protected according to the same standards as bank data. All information is stored in secure data centers with multiple backups in place. Also, HealthKit is HIPAA compliant.

Patient profiles and clinical notes in HealthKit can only be accessed by medical practitioners and administrators based on levels of access. Healthkit data can only be accessed with a username and password, and only people who have a user’s permission, such as doctors, can view a user’s personal information and health records. 

Apple's Health app

Read also: Our Healthcare Software Development Services


Letʼs check how easy it is to integrate your app with Google Fit and HealthKit. 

Google Fit 

Google asks developers to use its platform responsibly when developing fitness and wellness apps and lays out the following principles of use: 

  • It’s forbidden to use Google Fit for creating apps that store biometric or medical data without Google’s written consent.
  • Users should know what data you will collect and for what purpose.
  • You must honor requests from users to delete data.
  • If reading data from Google Fit, you must also allow for writing fitness data to Google Fit.
  • You must agree to the Google Fit Terms and Conditions before using the service.


First and foremost, to work with Google Fit you need a Google account and Google Play Services. You also need an OAuth 2.0 Client ID. Google provides extensive and clear documentation on how to make your app work with Google Fit.


Since HealthKit may be used for storing sensitive user data, Apple treats user privacy seriously and places strict rules on the platform.

  • Users should know what data you will collect and for what purpose.
  • Each user must explicitly grant each app permission to read and write data to HealthKit. Users can grant or deny permission separately for each type of data. To prevent possible data leaks, an app does not know whether it has been denied permission to read data.
  • HealthKit data must only be kept locally on users’ smartphones. For security, the HealthKit store can only be accessed by an authorized app. As a result, an app launched in the background cannot read data from the store.
  • While you can show advertising in an app that uses the HealthKit framework, you cannot use data from the HealthKit store to serve ads.
  • Any information gained through Healthkit cannot be exposed to a third party without user permission.
  • You can share a user’s HealthKit data with a third party for medical research only after the user grants permission.
  • You must provide a privacy policy for any app that uses the HealthKit framework.


Apple provides mobile app developers with a step-by-step guide on how to set up HealthKit. You need iOS SDK 8 or higher to work with HealthKit.

At this point, we’ve discussed the main data security and privacy issues related to HealthKit and Google Fit. Letʼs evaluate general risks and benefits associated with the effectiveness and accuracy of health tracking apps and wearables in general.

Are health and fitness apps and wearable devices reliable enough? 

While the mainstream use of health and fitness apps and the enormous popularity of wearables are undeniable, the level of trust that should be placed in the data they track and the degree of accuracy in diagnoses based on that data are controversial issues among experts. The main subject of academic disputes is the question of whether health and fitness apps together with wearable devices can bring more value or harm to end users.

Most studies claim that health and fitness apps and wearables can indirectly harm users by misreporting heart rate, blood pressure, blood sugar levels, and other data. This refers to the problem of inaccurate measurements of health parameters (either underestimation or overestimation, or just misclassification). In this case,  users with chronic diseases like diabetes may be affected adversely by misinformation. 

For instance, an individual with diabetes can get an incorrect glucose measurement and a device may recommend the user take the wrong dosage of insulin. This may result in low or high glucose levels, which can be detrimental to the health of the user and bring adverse drug events. Thatʼs why developers say that health and fitness apps as well as wearable devices are designed for educational and informational purposes only — as an alternative way to change health behavior. 

All in all, there is no clear winner between HealthKit and Google Fit. HealthKit focuses on providing very detailed information and stressing the health side of things, whereas Google Fit supports many more wearables and devices and is used for fitness app development. Despite all the advantages of both, each software development company should take all risks related to misdiagnosis or inaccurate tracking systems into account. 

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