Senior Full Stack Engineer I (Growth) in London

We are putting together a talented team to build the #1 training platform for runners. We help everyday runners become outstanding by building an incredible app providing world-class training, coaching and community for everyone, whether you are improving your 5k time or training for your first marathon. We are growing extremely fast! In November 2023, we closed a $6.5M funding round led by JamJar with participation from Eka Ventures, Venrex and Creator Ventures. In 2024, we were selected by Apple as one of three global finalists for the iPhone app of the year, reflecting the innovation and impact of what we have built. In 2025, we were acquired by Strava! Our ambition is huge: to become the go-to global leading training platform for millions of runners everywhere. We are growing with purpose and looking for people who want to build something meaningful with lasting impact. With the recent acquisition by Strava accelerating our journey, now is a really magical time to join.

The team you will join:

We are looking for a talented, curious and experimentation-minded Senior Full Stack Engineer to join the Growth Engineering team. This team owns key parts of the user journey into Runna, working across web and app to create high-quality experiences that turn first-time visitors into long-term, engaged subscribers. You will collaborate closely with product, design and data partners, as well as our founders and CTO, to shape how new users first discover and experience Runna.

What you will be doing:

• Architect, build, test and ship high impact user journeys and subscription funnels, focusing on turning curious visitors into active, engaged subscribers.
• Design and run experiments across web and app (such as onboarding flows, paywalls, and plan discovery experiences) to improve conversion at each step of the journey.
• Work closely with Product, Design and Data to prioritise opportunities, define clear success metrics and make decisions grounded in experiment results.
• Collaborate with other teams to ensure users have a smooth, consistent experience as they move between different products and platforms.
• Implement and maintain the instrumentation, tracking and tooling needed so we can understand behaviour, spot issues quickly and measure impact with confidence.
• Own features end-to-end: from early discovery and technical design through implementation, rollout, monitoring and iterative improvements.
• Contribute to our developer experience by improving CI/CD, testing and release workflows, enabling the team to ship and learn quickly.

What you will bring to the team:

• Strong TypeScript/JavaScript experience.
• Experience building user-facing product surfaces where conversion and UX really matter (onboarding, paywalls, landing pages, growth loops, etc).
• Comfortable working in a fast-paced, iterative environment with lots of experimentation and learning from data.
• 2+ years experience in your main expertise area (frontend, backend or full-stack).
• Skilled at delivering features end-to-end: from architecture and implementation through to rollout, measurement and iteration.
• You enjoy learning from experiments, and are as interested in what did not work as in the wins.
• Enthusiasm for our ways of working: Iterative development, continuous deployment and test automation.
• Knowledge sharing, pair programming and collaborative design.
• Shared ownership of code and outcomes across cross-functional teams.
• Experience working full-stack, or a strong interest in stretching across the stack.

Bonus points if you have:

• Experience with Swift or Kotlin for mobile, or Next.js for web experiences.
• Experience working on growth, experimentation, or funnel optimisation teams.
• Experience with analytics and experimentation tooling to support A/B tests.

Our Tech Stack:

• Frontend: React Native (iOS and Android), Typescript, GraphQL (Apollo Client), Fastlane, SwiftUI (Apple Watch), Maestro E2E tests.
• Backend: Serverless (AWS), Lambdas (NodeJS & Python), AWS AppSync, DynamoDB, S3, SQS, SNS, EventBridge, SageMaker, Snowflake.
• All the other good stuff: Sentry, GitHub Actions, Intercom, Mixpanel, RevenueCat, App Store Connect / Play Store, Google Tag Manager.

Salary and Benefits:

We are offering a salary of £70,000-£78,000 per year, depending on experience, plus participation in Strava's long-term incentive (stock) programs. Overview of our benefits is below: We are also committed to continually evolving our benefits to support you as we grow.

Here is a brief overview of what we currently offer in the UK:

• Flexible working – we typically spend 3 days a week together in our Vauxhall office.
• 25 days holiday, plus bank holidays (which you can take whenever suits you).
• Free Runna & Strava subscriptions for you and 3 of your friends.
• Headspace membership.
• Money every year to spend on gear, events and the gym!
• Private health insurance with Bupa and workplace pension scheme.
• Modern Health is a mental wellness platform and app that combines technology with professional support to improve mental well-being and reduce stress.
• Carrot fertility support - this benefits provider can provide inclusive fertility, hormonal health, and family-forming benefits to our global employee population.

Our Interview Process:

Our aim is to keep the interview process as straightforward and enjoyable as possible, and will consist of the following stages:

• Screening call with Talent team (30 minute video call).
• Getting to Know You + Live Coding (45-minute video call, first 25 mins will be an introductory chat followed by two live coding exercises).
• Take home technical task (max 1-2 hours to complete, or if you have something interesting you recently built and would like to showcase then that’s perfectly OK).
• 1.5-hour technical interview (the first half of the call will be used to discuss the take-home technical task from the previous stage and the second half will consist of system design and some general architecture/tech questions).
• Meet the team (in-person chat with founder(s) and rest of the team).

Please let us know if there is anything we can do to better accommodate you throughout the interview process.