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Full Stack Software Developer (PT)

Prorizon
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Part-Time Software Developer (Full Stack / Mobile App)
~20 hours per week | Remote/Hybrid | Immediate start 

UK-based applicants only please. 

Prorizon is a UK-based health & spors tech startup that utlises AI/ML to balance mind-body load for athletes. We are seeking a skilled Full Stack Mobile App Developer to join our sport and health technology start-up. Our core app has already been developed and the beta version is live with users. The role is focused on refining and advancing functionality, supporting iterative updates and enabling the integration of new machine learning and data science methods. You will work closely with our data scientists and wider science team to deliver high-quality solutions that bridge research and practice in sport and health.

The position requires someone who can take ownership of technical delivery, iterate rapidly and ensure reliability across the application. You will play a key role in supporting the development of the app, including but not limited to: API integrations, implementing push notifications, addressing bugs quickly and maintaining a seamless user experience across iOS and Android. Collaboration and communication are central, as the role involves translating analytic developments into robust and accessible features for end users.

What You’ll Do

  • Own the mobile app (Compose Multiplatform/Kotlin): performance optimisation,  ongoing support, constant improvement and platform compliance.
  • Own Node.JS Cloud server: ongoing support and new functionality development 
  • Manage Firebase Databases, Firebase Auth and Google Cloud.
  • Manage and develop integration with internal and third-party APIs; define contracts, handle auth, and manage schema changes safely.
  • Translate data-science prototypes into production features (model packaging, versioning, telemetry, fallbacks).
  • Build the delivery rails: CI/CD, automated tests, observability, and lightweight release notes.
  • Triage, fix, and learn from production issues; keep quality and speed in healthy tension.
  • Collaborate closely with the Tech Lead, data scientist and sub-contractors; contribute to our evolving product/tech roadmap.

Technical requirements:

  • Strong experience with Compose Multiplatform, with a proven track record of successfully delivering multiple development projects. 
  • In-depth understanding of core principles for both iOS and Android development and thorough knowledge of App Store and Google Play rules and requirements. 
  • Hands-on experience with Node.js in Google Cloud, and knowledge of Firebase Cloud and its ecosystem. 
  • Proven ownership of CI/CD pipelines and release automation for iOS and Android (e.g., GitHub Actions/Bitrise + Fastlane/TestFlight/Play Console). 
  • Hands-on with crash/error monitoring and analytics instrumentation (e.g., Crashlytics/Sentry + analytics), plus feature flags for safe, iterative releases. 
  • Push notifications end-to-end: APNs/FCM setup, permissions, payload design, and testing. 
  • API integration expertise: auth, contract design, schema change management, and robust error handling. 

Other Skils:

  • Confident in testing strategy (unit/UI), raising coverage, and stabilising/ documenting a vendor-delivered codebase. 
  • Able to triage, ship, and learn quickly, maintaining a weekly release cadence. Availability ~20 hours/week and ability to start promptly. 
  • Clear communicator who can translate R+D prototypes into production-grade features with telemetry and fallbacks. 

Desirable:

  • Native platform depth: Swift (iOS) and Java/Kotlin (Android) for performance tuning and edge cases. 
  • Experience with A/B testing, performance profiling, and lightweight engineering dashboards. 
  • Back-end/API experience and simple admin tools to support operations. 
  • Experience productising data-science/ML prototypes (model packaging, versioning, latency budgets).
  • A postgraduate degree in CS/SE or equivalent professional track record.
  • Interest in sport/health/performance and sensitivity to privacy and regulatory basics.
  • Experience in building web apps in addition to mobile. 
  • Leadership. Prorizon is a small team working hard to deliver a great product. Therefore, there will be times where you will have to make decisions for yourself and guide the company given your expertise. 

This role offers the opportunity to join a venture that is redefining how health and performance are measured and managed. Our solution integrates bio-psycho-social data into a unique mind–body load digital twin model, generating actionable insights that reduce risk, optimise recovery and enhance performance. Backed by Innovate UK and already in the hands of athletes, we are moving fast to scale our impact. For the right developer, this is a rare chance to shape a live product at the intersection of science, sport and technology, ensuring that cutting-edge analytics become practical tools for meaningful change in health and performance. 

To apply, please send a cover letter and CV to joly@prorizon.tech