Wearable and BLE app development at Mercury Development covers pairing, watchOS and Wear OS apps, and Apple HealthKit sync. We have been building Bluetooth Low Energy products since 2012, from Kensington's tracking tags to Tonal's connected trainer.
Almost nobody arrives at the idea stage. They arrive with hardware that already exists and software that is not keeping up with it. Three situations account for most of those calls.
A day of steps shows up as one lump instead of hour by hour. Calories go missing, sleep never syncs on Android. We rebuild the sync layer and verify it against physical sensors, so users see what the device actually recorded.
Your device has a ship date and your app has a backlog. Finished units sit in a warehouse with nothing to pair to. We put a working pairing flow into the first sprints and size the team against your hardware dates.
The first integration gets written around one chipset. Add a second sensor brand and the whole connection layer needs a rewrite. We build that layer to take new devices from day one and hand over protocol docs with the code.
A day of steps shows up as one lump instead of hour by hour. Calories go missing, sleep never syncs on Android. We rebuild the sync layer and verify it against physical sensors, so users see what the device actually recorded.
Your device has a ship date and your app has a backlog. Finished units sit in a warehouse with nothing to pair to. We put a working pairing flow into the first sprints and size the team against your hardware dates.
The first integration gets written around one chipset. Add a second sensor brand and the whole connection layer needs a rewrite. We build that layer to take new devices from day one and hand over protocol docs with the code.
Some clients hand over the whole connected product. Others need one part done properly: a pairing layer, a watch app, or a device test pass before launch. Each service below works either way.
Pairing, reconnection, and BLE GATT communication with your device. With standard BLE or ANT+ sensors, a shared data layer makes each new brand quicker to add.
Native watchOS apps in Swift and SwiftUI, and Wear OS apps in Kotlin. We built the watchOS app for Tonal's home gym, synced live with the machine.
iOS and Android apps that pair with your device and carry the experience around it. Kensington's BLE accessories run on iOS, Android, Windows, and macOS.
Two-way sync with Apple HealthKit, Google Fit, and Google Health Connect. We also build against Garmin Connect and Strava where a public API exists.
The kit other developers use to support your hardware. For Bladepad we shipped an Objective-C SDK and a Unity 3D plugin, so game studios added support themselves.
Connectivity and functional tests on real hardware, not simulators. Every BLE build gets a device pass across the sensor brands and OS versions your users own.
Mercury Development has shipped software since 1999 and Bluetooth Low Energy products since 2012, for clients from startups to Fortune 500 companies. Every engineer has at least 3 years of experience and team leads have 7 or more. On Clutch that work holds a 5.0 rating across 34 verified reviews.
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Our connected device work runs from home gym equipment to Bluetooth accessories and game controllers. Tonal, Kensington Proximo, Bladepad, and Fitbit each brought a different connection problem. The next section takes them one at a time.
Tonal already had Android trainers and mobile apps running. We built the watchOS app and the session logic that keeps one workout in sync across all three at once.
Real-time Apple Health sync across three devices
Bluetooth and ANT+ heart rate monitors both supported
SwiftUI combined with Apple Combine before its release
Built onto an existing Flutter-based iOS app
Kensington needed Proximo tags on Android while Android still had no BLE support. We built against a pre-release Samsung SDK that covered one handset, and shipped a working app in 3 months.
Working Android app delivered in 3 months
BLE clients on iOS, Android, Windows, and macOS
Product recognized with a 2013 CES Innovation Award
Bladepad needed game studios to support its Bluetooth controller, which meant the deliverable was a kit rather than a product. We wrote the SDK and a plugin for the engine those studios already used.
Over 50 games supported before public launch
Objective-C SDK plus a Unity 3D plugin
Calibration app to correct the joystick response curve
In 2011 Fitbit was a startup with a clip-on step counter and new technology. We built the tracking apps and the social network around them, then stayed with the product for a decade.
Apps used by more than 50 million people
10 years on the same product line
Mobile and web platforms, plus a social network
A connected product runs on two schedules, yours and your firmware's. Work moves in two-week sprints with a demo at the end of each, so software progress stays visible against hardware dates. You own the code at every stage, and the team resizes between phases.
We start on the hardware. What the device advertises over BLE, which characteristics matter, what the firmware handles, where health data lands: the estimate is built on that list.
Flows and screens for every connection state: searching, pairing, syncing, disconnected, low battery. Awkward states get solved on paper, where a change costs a drawing, not a sprint.
Review and feedback sessions are part of this phase, so flows get fixed while still drawings. The number of rounds is set in the estimate, so design never runs open-ended.
Sprint builds with planning and a demo every other week. Each demo runs on real hardware, so you judge progress against your launch date instead of reading a status report.
Functional and connectivity tests on the devices, sensors, and OS versions your users carry. No simulator can fake a dropped connection, a sleeping phone, or a dying battery.
We handle App Store and Google Play submission for the companion app. The same team then stays on for monitoring, OS updates, and changes your firmware roadmap brings.
This is the stack behind the work above. Native code where pairing and battery life decide the experience, cross-platform where budget decides it. Health data is handled to the standards regulators expect.
Apple Watch and watchOS, Wear OS and Android wearables, plus Google Glass and tvOS. Desktop clients on Windows and macOS when an accessory needs them.
Swift, SwiftUI, Apple Combine, and Objective-C for Apple, Kotlin and Jetpack Compose for Android. Flutter or React Native for shared code, and C++ for device logic.
Bluetooth Low Energy, GATT services and characteristics, ANT+ for heart rate and sensor data. We also work with vendor SDKs and proprietary hardware protocols.
Apple HealthKit, Google Fit, Google Health Connect, Garmin Connect, and Strava. Workouts, heart rate, sleep, and activity sync into your app and back out.
AWS and Azure backends in Python, Go, and .NET on Kubernetes. They hold up when a gym full of devices syncs at once, and your team runs devices from an admin panel.
We build to HIPAA, GDPR, CCPA, and SOC 2 requirements, with WCAG for accessibility. We document how each product stores, shares, and deletes health data.
Mercury Development has met all the client's project goals and exceeded their expectations. The team has managed the project in detail, hit all deadlines, managed expectations, and reprioritized tasks. Moreover, they've understood the client's business and become a true partner.
Mercury Development delivered the project on time with a structured approach and strong technical expertise. The engagement resulted in higher customer satisfaction, improved retention, and better regulatory compliance. Communication was through email, messages, and weekly virtual meetings.
Development provides software integration and mobile app development for turnkey retail platforms, ensuring up-to-date functionality and system cohesion by scaling from 2–10 resources as needed. The team’s precise task breakdowns, affordable price point, and proactive reporting strengthen the partnership.
We’ve actually brought Mercury in across three totally different companies. First it was an app for car sales, then later they stepped in to fix a fire safety app that needed help, and now they’re building stuff for a valve manufacturer. Kinda shows they can jump into all sorts of industries and just get the work done.
Mercury Development consistently delivers high-quality codes that the client has never seen from a contract organization. They've not only contributed to existing features but have also led the development of new initiatives. Overall, the client is impressed with the vendor's talented engineers.
Mercury Development has helped the client with all kinds of developments and acquisition plans. They were quickly able to familiarize themselves with the business, industry, and products. The team maintains strong control of the timelines and budget but remains open to changes and client requests.
Mercury is very organised and there are no hidden surprises. They first scoped the project in detail, questioning the specification supplied as necessary. They also focussed on the success testing right from the start. I was also guided through the process so it was very straight-forward.
Mercury was awesome, they were reasonably priced, and took ownership over the project from the get-go. The code is clean, the app is polished, and they made multiple revisions very easy and at no additional charge. I would highly recommend working with them again, especially if you need an Apple TV app built with an API to your YouTube channel.
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