Senior Mobile Developer

The Role:

We're hiring a Senior Mobile Developer to help build and scale the Numan app on iOS and Android.

For many patients, the app is Numan. It's where they complete their consultation, manage their treatment and subscriptions, book and track tests, message their clinician and health coach, and follow their programme day to day. When it's fast, clear and reliable, patients stay on track with their health. When it isn't, they drop off.

You'll work in a cross-functional squad with product, design and backend engineers. You'll own features from idea to App Store and Google Play, shape the app's architecture, and raise the bar on quality across the mobile team. This is a Level 5 (Senior Engineer) role in our engineering framework: you'll deliver large features across a whole product area, think holistically about the app, and collaborate with and mentor the engineers around you.

You'll be working with special category health data, so privacy, security and accessibility are part of the job, not an afterthought.

You will:

• Design, build and ship features in the Numan app, owning them from technical scoping through release and post-launch monitoring.

• Write production-quality native code in Swift and SwiftUI (iOS) or Kotlin and Jetpack Compose (Android), with strong test coverage.

• Shape and evolve the app's architecture: modularisation, state management, networking, offline behaviour and how we share patterns across platforms.

• Work with product and design to turn patient problems into simple, accessible experiences, and push back when a simpler approach would serve patients better.

• Partner with backend engineers on API design so the app gets the data it needs, efficiently and securely.

• Own app quality: crash rates, performance, startup time and accessibility (WCAG). Use monitoring and analytics to find and fix problems before patients notice them.

• Improve our mobile delivery pipeline: CI/CD, automated testing, feature flags, phased rollouts and App Store / Google Play release management.

• Protect patient data. Build with secure storage, authentication and privacy in mind, in line with UK GDPR and healthcare requirements.

• Give thorough, constructive code reviews and write clear documentation, RFCs and PR descriptions.

• Mentor other engineers, share knowledge across the mobile team, and help set standards and working practices.

• Interview candidates and help us grow the team.

• Use AI coding assistants thoughtfully to move faster without lowering the bar on quality.

You'll have:

• 5+ years building mobile apps professionally, with at least one consumer app you've helped ship and scale on the App Store or Google Play.

• Deep expertise in native development on at least one platform: Swift and SwiftUI (iOS) or Kotlin and Jetpack Compose (Android). Working knowledge of the other platform is a plus.

• A strong grasp of mobile architecture (for example MVVM, unidirectional data flow, dependency injection, modularisation) and the judgement to know when to keep things simple.

• A testing mindset: unit, UI and snapshot testing, and experience building testable code.

• Experience with CI/CD for mobile (for example Fastlane, Bitrise, GitHub Actions or Xcode Cloud) and managing releases end to end.

• Experience integrating with REST or GraphQL APIs, handling auth, caching and error states well.

• A track record of owning large features or product areas and improving the engineering practices of the team around you.

• Experience mentoring engineers and giving useful code reviews.

• Clear communication with engineers and non-engineers alike, and comfort working closely with product and design.

• Care for patients and an understanding of why privacy and accessibility matter in health products.

• Experience working in an agile team, delivering in sprints and working effectively with product and design to deliver real value to customers often.