Senior Modelling Engineer II

Runna; Greater London; Hybrid; GBP 85,000 - 95,000; Full time

Benefits offered by this job

Flexible working

25 days holiday plus bank holidays

Free Runna & Strava subscriptions

Headspace membership

Annual spending allowance for gear

Private health insurance

Mental wellness support

Fertility support

Job summary

A leading fitness technology firm based in Greater London is seeking a Software Engineer with expertise in Python to join their Train Team. You will be responsible for building and delivering innovative training features, leveraging data-driven approaches, and coaching fellow engineers. The role offers a competitive salary of £85,000-£95,000 per year along with substantial benefits, including flexible working conditions and health insurances. Join a fast-growing team focused on creating the #1 training platform for runners.

Qualifications

• Minimum of 5 years experience in software engineering or modeling.
• Experience with large Python projects and scalable design patterns.
• Ability to lead complex technical projects from inception to completion.

Responsibilities

• Build and deliver new training features.
• Experiment with algorithms to improve training systems.
• Coach engineers and provide mentorship.

Skills

Python programming

Algorithm design

Project leadership

Collaboration

Analytical skills

Testing and quality assurance

Education

Computer Science degree or equivalent

Job description

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.

As a cross‑functional (engineering, product, design, coaching) team of >35, the Train Team works at the heart of Runna’s mission: delivering the best training possible to hundreds of thousands of runners worldwide. From creating and dynamically adjusting optimal, personalised training plans at scale, to analysing performance data to make training adjustment recommendations, to providing insight to users derived from their training and environment – we do all things training technology.

We follow a flexible hybrid model that translates to more than half of your time on‑site – 3 days per week in Runna’s office based in London, UK.

What You’ll Do

• Building, testing and delivering new and improved training features (such as strength plans, post‑injury plans, illness, weather etc).
• Experimenting to improve our training system with new algorithms, design patterns, optimisations and modelling approaches.
• Coaching and supporting engineers, providing guidance, mentorship, and code reviews without creating bottlenecks.
• Collaborating with coaches to best deliver their expertise to users.
• Using a data‑led approach to influence algorithms where possible.
• Designing and implementing test approaches to ensure consistency and accuracy of training.

What You’ll Bring To The Team

• We’d generally expect ~5+ years of experience in a software engineering, modelling focussed position for this role, however expect this to vary candidate to candidate!
• Proficiency in Python (object‑oriented) programming, with experience writing production‑quality code – a bonus for large python projects and leveraging scalable design patterns effectively.
• Ability to design and implement complex algorithms and modelling components (e.g. exercise scheduling), and comfortable with quantitative methods and approaches to solving problems – gained through various experiences or studies (e.g., Computer Science, Mathematics, Physics, Engineering degree or equivalent practical experience).
• Ability to lead complex technical projects from inception to completion, whilst effectively collaborating with cross‑functional (e.g. product) teammates.
• Demonstrate best practice in your own work, as well as coaching other engineers to elevate the quality and velocity of the team.
• Testing modelling focused software to ensure quality and maintainability.
• A pragmatic mindset, with excellent communication and collaboration skills.
• Analytical and detail‑oriented, with a commitment to producing high‑quality work.
• Enthusiasm for our ways of working which include
  • Working in a fast‑paced, iterative environment whilst maintaining engineering quality
  • Iterative development, continuous deployment and test automation
  • Knowledge sharing, pair programming, collaborative design & development
  • Shared code ownership & cross‑functional teams

It’d Be a Bonus If You

• Experience with deployment, release cycles or CI/CD.
• Experience delivering features end‑to‑end: from design, to implementation through to releasing, testing and supporting.
• Experience in a product‑focused organisation, building consumer‑facing applications.

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) programmes.

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 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.
• 📱 Free Runna & Strava subscriptions for you and 3 of your friends (get ready to be your friend’s 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.

Compensation Range: £85K - £95K