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 https://www.strava.com/about?hl=en-GB! 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 Senior Backend Engineer (II) to join our Special Projects Team, the team responsible for building Runna features directly inside the Strava app. You'll design and build the services that let Strava athletes experience Runna's structure training and workout analysis natively within Strava. This is a rare chance to shape how two products with tens of millions of combined users connect at the data and platform level. We follow a flexible hybrid model that translates to more than half of your time on-site in our London office — three days per week. WHAT YOU’LL BE DOING: - Design, build, and maintain scalable backend services using Strava’s tech stack (Ruby, Java, Scala, Python, Go, MySQL, Redis, Cassandra, Kafka, Kubernetes, Docker, Elasticsearch, and GraphQL). - Develop and optimise APIs that seamlessly integrate with client-facing applications to deliver impactful features. - Partner directly with Strava engineering teams in San Francisco and Berlin to align on data contracts, service boundaries, and integration patterns, which will involve some overlap with US and CET working hours - Collaborate with cross-functional partners, including product managers, designers, and client-side engineers, to align technical implementation with business needs. - Mentor and support other engineers, fostering a culture of learning, growth, and technical excellence. - Ensure service reliability, scalability, and performance while balancing technical debt with new feature development. - Act as a go-to resource on Strava's backend stack for the wider Runna engineering team, building that fluency through pairing, code review, knowledge-sharing sessions etc. WHAT YOU’LL BRING TO THE TEAM: - You have 5+ years of professional software development experience or equivalent expertise in backend engineering. - You are proficient in at least one of Strava’s core backend languages (Ruby, Java, Scala, Python, or Go). - You have experience with relational (e.g., MySQL) and NoSQL (e.g., Redis, Cassandra) databases in production environments. - You have a solid understanding of distributed systems, API design (GraphQL is a plus), and technologies like Kafka, Kubernetes, and Docker. - You excel at mentoring engineers and fostering a positive, growth-oriented team culture. - Comfort working with colleagues across US and European time zones, with occasional flexibility on working hours to enable that overlap SALARY AND 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 is 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) -…