Senior Backend Engineer II

We're 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're improving your 5k time or training for your first marathon. We’re 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’ve 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’re 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’ll join We’re looking for a talented, curious and experimentation minded Senior Full Stack Engineer to join 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 longterm, engaged subscribers. You’ll 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'll be doing Architect, build, test and ship high impact user journeys and subscription funnels , taking technical ownership across multiple workstreams and setting the standard for how the team approaches conversion engineering. Lead the technical strategy for experimentation across web and app — defining how we run, instrument and learn from experiments at scale, not just executing individual tests. Work closely with Product, Design and Data to shape the roadmap , proactively identifying opportunities across teams and ensuring our technical investments balance long term scalability with shorter term business goals. Identify and align with other engineering and product teams whose work intersects with Growth, driving cross-team coordination to deliver consistent, high-quality user experiences across the platform. Own and evolve the instrumentation, tracking and tooling strategy for the team — establishing standards for how we measure behaviour and impact, and guiding other engineers in applying them. Own features end‑to‑end and drive the technical direction of larger, multi-milestone projects — coordinating across engineers, managing sequencing and dependencies, and communicating risk to cross-functional stakeholders. Elevate our engineering culture by improving CI/CD, testing and release workflows , and establishing coding standards and best practices that raise the bar for the whole team. What you'll bring to the team: Strong TypeScript/JavaScript experience, with a track record of establishing patterns and standards that other engineers adopt. Experience building user-facing product surfaces where conversion and UX really matter , and an ability to shape the technical direction of those surfaces — not just deliver features within them. Comfortable leading in a fast-paced, iterative environment — setting the technical vision for how the team experiments and learns, and helping others do the same. 3+ years experience, with depth in at least one area of the stack and the range to contribute meaningfully across it. Skilled at delivering large, complex projects end-to-end: from architecture and technical design through phased rollout, measurement and iteration — with the ability to coordinate multiple engineers across stages. You think deeply about what didn't work and why , and translate those learnings into better processes, frameworks or tooling for the team. Enthusiasm for — and ability to actively shape — 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, with a willingness to guide and mentor others across the stack as needed. Compensation Overview & Benefits: We’re offering a salary of £85,000-£95,000 per year, depending on experience, plus participation in Strava's long-term incentive (stock) programs. Overview of our benefits are below: We’re also committed to continually evolving our benefits to support you as we grow. Here is a brief overview 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 (get ready to be your friends fave person or save them for holiday presents!) 🧘 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 and takes the burden off what we know can be a stressful process. Please let us know if there’s anything we can do to better accommodate you throughout the interview process - this can be from scheduling interviews around childcare commitments to accessibility requirements. We want you to show your best self in the process, so please speak to your Talent Partner!