Senior Modelling Engineer I

• Build, test, and deliver new and improved training features such as strength plans, post-injury plans, illness and weather adjustments at scale. • Experiment to improve Runna's training system with new algorithms, design patterns, optimisations, and modelling approaches. • Use a data-led approach to influence algorithms, and design and implement test approaches to ensure consistency and accuracy of training. • Coach and support engineers through guidance, mentorship, and code reviews without creating bottlenecks. • Collaborate with coaches to best deliver their expertise to hundreds of thousands of runners worldwide. • Work in a hybrid pattern with 3 days per week in Runna's Vauxhall office.

• Have around 3+ years of experience in a software engineering or modelling-focused position. • Have proficiency in Python (object-oriented) with experience writing production-quality code. • Have the ability to design and implement complex algorithms and modelling components such as exercise scheduling. • Be comfortable with quantitative methods and approaches to problem-solving — gained through CS, Mathematics, Physics, Engineering, or equivalent practical experience. • Have experience testing modelling-focused software to ensure quality and maintainability. • Bring a pragmatic mindset with excellent communication and collaboration skills. • Be analytical and detail-oriented with a commitment to producing high-quality work.

• Have experience with deployment, release cycles, or CI/CD. • Have experience delivering features end-to-end from design through implementation to release, testing, and support. • Have experience in a product-focused organisation building consumer-facing applications. • Have experience with large Python projects and scalable design patterns.

• Build and improve training features across Runna's core training engine. • Experiment with new algorithms and modelling approaches to improve training quality. • Design and implement test approaches to ensure consistency and accuracy. • Mentor and support engineers through code reviews and collaborative design. • Collaborate cross-functionally with coaches, product managers, and designers. • Contribute to knowledge sharing, pair programming, and shared code ownership across the Train team.

Runna is one of the most exciting fitness startups in the UK right now, and the Strava acquisition only makes the opportunity bigger. In under four years from launch, Dom and Ben built Runna from a website selling personalised PDF training plans to a globally rated running coaching app, a finalist for Apple's iPhone App of the Year, and ultimately an acquisition by the world's largest fitness community. The team has grown to over 150 people across London and Boston, and Strava has publicly committed to investing further in growing both the team and the product. What stands out on Glassdoor (4.9/5 from 31 reviews, with 100% of employees recommending it) is how consistently people praise the culture, the kindness of their colleagues, and the quality of the leadership. Benefits are genuinely strong for a company this size: private health insurance, enhanced parental leave (up to 20 weeks fully paid), Strava equity, a smartwatch as you pass probation, 25 days holiday plus bank holidays, and a paid hour each week to go for a run during work hours. They operate a flexi-hybrid model, typically three days a week in their Vauxhall office. The team runs bi-weekly together, and Workout Wednesdays include exercise plus a free lunch. The main thing to be aware of is that this is a fast-paced startup environment where priorities can shift quickly, which some reviewers flag as a challenge. There is also a slight bias toward hiring passionate runners, though this has been improving. If you want to work on a product that helped millions of runners train, alongside kind and ambitious people, with the backing and scale of Strava behind you, Runna is a brilliant opportunity.

• Earn £70,125–£78,375 per year plus participation in Strava's long-term incentive stock programmes. • Work in a hybrid pattern with 3 days per week in the Vauxhall office. • Take 25 days holiday plus bank holidays. • Access free Runna and Strava subscriptions for yourself and 3 friends. • Receive a Headspace membership and Modern Health mental wellness platform access. • Access private health insurance with Bupa and a workplace pension scheme. • Receive an annual budget for gear, events, and gym. • Access Carrot fertility and family-forming support.

Runna is building the number one training platform for runners — helping everyday runners become outstanding through world-class training, coaching, and community. Selected as an Apple iPhone App of the Year finalist in 2024 and acquired by Strava in 2025, Runna is growing fast with huge global ambitions. The Train Team is a cross-functional team of 35+ working at the heart of Runna's mission — delivering the best personalised training possible to hundreds of thousands of runners worldwide.