Junior Software Engineer (Mobile App)

Recoreo is hiring our first junior engineers to help scale Gym Geek: The Smart Calorie Counter That Keeps You on Track. Launched in June 2025, our app has helped over 300,000 people lose, maintain or gain weight. We’re rated 4.8 stars on the App Store, and we’re quickly gaining market share with our unique take on weight management.

We’re now hiring our first engineers to take Gym Geek through the next stage of growth. This is an exciting opportunity to work closely with the product, users and contribute to the technical direction of the business.

As a junior engineer at Recoreo, you’ll work with a wide range of technologies, across our mobile app, web front-end and back-end APIs. We don’t expect prior experience in all areas, but you should be eager to learn beyond a single speciality.

What we’re looking for

  • You’ve already built and shipped at least one small app, website or meaningful project.
  • You have graduated (or will graduate) with a degree in computer science or related STEM field.

Technology we use

We use a wide range of languages and technologies, but don’t worry: we don’t expect you to have prior experience in all areas. Although we expect junior engineers to learn quickly, we’ll put in place the support, mentorship and growth opportunities for you to gain experience over your first 6-12 months:

  • Expo/React Native/Typescript - Our mobile app is written in Typescript, leveraging the Expo framework. We use SQLite to persist user data. Very occasionally, we might need to write small amounts of Objective-C, Swift or Java.
  • React/Typescript - Our website is built with React and Typescript, and serves both long-form content as well as interactive content like our calorie calculators and macro calculators.
  • Node.js/GraphQL - A single GraphQL server is the back-end for both our mobile app and website, serving content and metadata, food database search results and remote configuration for our app.
  • AI - embeddings + chat completions - We use OpenAI models, including text vector embeddings and the chat completions API (i.e. “chat model”), to support various features in our app. We plan to introduce more AI features into our app over the coming year.

Engineering principles and culture

  • No silos - Engineers at Recoreo work across the entire stack, from mobile (~50%), frontend (~30%) and backend (~20%); using a diverse range of programming languages and technologies.
  • We bias towards pairing - We tend to work together on complex or high-leverage problems more than typical engineering teams. We believe that pairing helps us move and learn faster, reduce mistakes and leverage our different perspectives and skillsets. For junior engineers, it’s a great way to onboard and build confidence with our codebase.
  • We prioritise mentorship and growth - We expect engineers to learn quickly, and we put in place the support, mentorship and growth opportunities to make it happen. Junior engineers are supported through regular pairing, code reviews and close collaboration with other engineers in the team.
  • We experiment and learn - We don’t just build for the love of building. We’re grounded in experimentation and measurement. Every time we ship, we assess our success by measuring a metric or outcome. That could be something technical (like latency or reliability) or something product or commercial (like a conversion or retention rate).

What we’re currently working on

Here’s a flavour of the kind of projects you might work on at Recoreo:

  • Apple Health integration - Our Apple/Google Health integration will allow users to track their activity level, as well as their calorie intake, in the Gym Geek app. Our Smart Calorie Adjustments feature, which adjusts a user’s calorie goal to keep them on track, will also need to be improved to factor in activity as well as calorie intake. This project is mostly front-end work, with a little math/stats to make the Smart Calorie Adjustments work correctly.
  • User authentication - We will introduce authentication (sign in with Apple, Google, etc) to allow users to sign in across multiple devices, and back-up their data to the cloud. We’ll also allow users to opt-in to reminder emails, which will improve our short-term retention and user activation. This project is a mix of front-end and back-end work.
  • AI insights - We plan to introduce more AI features into our app, to give users better insight into their progress. To start, we will build an AI overview feature in our Insights tab to give users day-to-day feedback. This is a mix of front-end, back-end and AI prompting work.

You can find more information about your tech, culture and projects on our website: https://recoreo.com/careers/engineering

Practical details

  • Location: City of London.
  • Hybrid/remote: Due to our working style, hybrid or remote working is not typically available for this role.
  • Sponsorship: Sorry, we are not able to sponsor visas at the moment.
  • Salary range: £TBD

How to apply