How to choose the right wearables API for your fitness & wellness app

The wearables integration challenge: Why a unified wearables API helps

Integrating wearables data seems straightforward until you start building. Each device manufacturer offers their own API with unique authentication flows, data formats, and rate limits. What looks like a simple integration quickly becomes a complex web of different endpoints, OAuth implementations, and data normalization challenges.

Consider what happens when you want to support the most popular wearables. You'll need separate integrations for Apple HealthKit, Google Health Connect, Fitbit, Garmin, Oura, and potentially dozens of others. Each requires different implementation approaches, testing strategies, and most importantly – ongoing maintenance.

The technical complexity multiplies when you factor in data consistency. Heart rate data from an Apple Watch arrives in different units and formats than the same metric from a Garmin device. Your infrastructure will need to normalize this data while maintaining accuracy and handling edge cases like missing data points or device sync delays.

That’s why correct wearables API selection is critical. The right choice accelerates development, while the wrong one can derail your entire project timeline and cause costs to skyrocket.

Direct wearable API vs. Unified wearables API

You have two primary approaches for wearable data integration: connecting directly with each device provider via API or SDK, or using a unified wearables API that aggregates multiple wearables through a single interface.

Direct integration: Maximum control, maximum complexity

Building direct integrations gives you complete control over the user experience and data handling. You implement each manufacturer's API or SDK, manage their specific authentication requirements, and handle data processing exactly how you want.

However, this approach requires significant development resources. You'll need to:

• Implement and maintain separate codebases for each wearable platform
• Handle different OAuth flows and authentication token management
• Normalize data formats across multiple APIs
• Stay updated with each manufacturer's API changes and deprecations
• Test across different device types and OS versions
• Manage varying rate limits and API quotas

The maintenance burden grows with each additional wearable you support. Every manufacturer update, new device release, or API change requires dedicated engineering attention.

Unified wearables API: Faster implementation, consistent experience

Unified wearable API platforms solve the complexity problem by providing a single integration point for multiple devices. Instead of managing dozens of different providers, you integrate once and gain access to hundreds of wearables.

Platforms like Spike API handle the heavy lifting: OAuth flows, data normalization, rate limit management, and ongoing API maintenance. This means your development team can focus on creating user value rather than wrestling with integration challenges.

“Spike gave us a huge shortcut. It would've taken months to get wearables working right — and even then, we'd still have to maintain them. Now we just build on top,” Kevin Lam, from Built With Science, describes his experience with Spike.

Spike's pricing scales with your success, making it accessible for startups while providing enterprise-grade reliability for larger applications. The platform now offers an all-in-one SDK that supports multiple development frameworks including Kotlin, Swift, Flutter, and React Native, significantly reducing both development time and costs. Advanced features like background delivery support for Android, Samsung Health, Huawei Health, and iOS ensure seamless data collection at all times.

Key evaluation criteria

When evaluating wearable API options, focus on factors that directly impact your development timeline and user experience.

Device coverage and market reach

The best wearables API means nothing if it doesn't support the devices your users actually wear. Evaluate platforms based on their coverage of popular consumer wearables, including fitness trackers, smartwatches, and specialized health devices.

Spike wearables API integrates with 500+ devices and apps, covering major brands like Garmin, Fitbit, Oura, Apple HealthKit, and Whoop, with recent additions including COROS, Ultrahuman, Huawei Health, and Samsung Health. This broad coverage ensures you can serve most users without forcing them to switch devices.

Look for platforms that regularly add new device support without requiring changes to your integration setup. The wearable market evolves rapidly, and your API choice should evolve with it through direct API approaches that enable richer metrics without additional development overhead.

Data types and granularity

Different wearables excel at different types of data collection. Some focus on activity tracking, others prioritize sleep analysis or heart rate monitoring. Your API platform should provide access to the specific metrics your app needs.

Consider both the breadth of available data types and the granularity of that data. Heart rate monitoring requires different API capabilities than daily step counts. Ensure your chosen solution can deliver data at the frequency and detail level your features require.

Spike API already offers enhanced health metrics including VO₂ Max, ECG, weight, sleep data, and more. Advanced analytics features like Sleep Score combine detailed sleep metrics to offer quick snapshots of sleep quality, while Stress and Activity Scores provide deeper health insights for your users.

Authentication and user experience

User onboarding makes or breaks wearable integrations. Complex authentication flows create friction that prevents users from connecting their devices. Look for platforms that streamline the connection process while maintaining security standards.

Data consistency and reliability

Wearable data arrives in different formats, units, and structures depending on the source device. Your chosen wearables API platform should normalize this data into consistent formats that your app can rely on.

Testing is crucial, focusing on functionality, performance, and security when evaluating API reliability. Look for platforms that provide consistent uptime, handle device sync delays gracefully, and offer clear documentation about data accuracy and limitations.

Scalability and performance

Your wearable integration needs to scale with your user base. Evaluate API platforms based on their ability to handle increased load, rate limiting policies, and data processing capabilities.

Consider both current needs and future growth. An API that works well with a few hundred users might struggle as you scale to thousands. Look for platforms with proven track records at enterprise scale.

Implementation timeline considerations

Your choice between direct integration and unified wearables API significantly impacts development timelines.

Direct integration timeline

Building direct integrations with multiple wearable APIs typically requires several months of development work. You'll need to:

• Research each manufacturer's documentation and requirements
• Implement separate authentication flows for each platform
• Build data normalization and processing logic
• Create testing workflows for different device types
• Handle ongoing maintenance and updates

This approach makes sense if you have the resources to spend time on ongoing maintenance and API upgrades.

Unified platform timeline

Unified wearable APIs can reduce implementation time to days or weeks rather than months. Most platforms provide in-depth documentation, SDKs for popular development frameworks, and support teams to assist with integration and ongoing maintenance.

The faster time-to-market often justifies the ongoing costs through earlier revenue generation and competitive advantages.

Making the strategic decision

For most development teams, the choice comes down to resource allocation and strategic priorities. Do you want to invest engineering time in wearable integration maintenance, or focus those resources on features that differentiate your product?

When direct wearables integration makes sense

Choose direct integration if you:

• Need deep customization of the user experience
• Only plan to support one or two specific wearables (e.g., just Garmin users)
• Have dedicated resources for ongoing wearables integration maintenance

When unified wearables API excel

Unified wearable APIs work best when you:

• Want to support multiple wearable devices quickly
• Prefer predictable development timelines
• Need to focus engineering resources on core product features
• Want ongoing device support without additional development work
• Require enterprise-grade reliability and compliance
• Need background data collection capabilities across multiple platforms

Ready to integrate wearable data?

The right wearable API choice accelerates your development timeline while ensuring your users can connect their favorite devices seamlessly. Whether you choose direct integration or a unified wearables API depends on your specific requirements, resources, and strategic priorities.

Spike’s wearables & IoT API offers full wearable device integration support for 500+ popular fitness trackers, smartwatches, and health devices. With over 200 healthcare organizations already leveraging unified wearable APIs and billions of data points being processed daily, the infrastructure exists to support applications of any scale. From startups building their first health app to enterprises requiring AI-ready data pipelines.

Ready to see how quickly you can scale by adding wearable integrations to your app? Book a demo or check out our documentation.