Mid-Senior Product Engineers (Polyglots) in London

Requirements

While much of our product runs on Ruby today, we’re deliberately hiring polyglot engineers because diverse technical backgrounds make our teams stronger — different languages shape how you solve problems, reason about systems, and design clean software. If you’ve shipped meaningful product work in any modern stack, you’ll ramp quickly here. What matters most is curiosity, thoughtful engineering, and a willingness to learn, not a perfect match on our tech. We value engineers who think clearly, understand trade-offs, and can apply strong fundamentals to any language or framework.

You care about building products that genuinely help people, and improving financial health is a mission that resonates with you. You’re an engineer with solid fundamentals who has worked in any modern tech stack – the exact language isn’t important. What matters is your ability to reason clearly, learn quickly, think in trade-offs, and write maintainable, thoughtful code. You collaborate well with product, design, and data; you’re curious about users; and you enjoy shaping work beyond just the technical bits.

Whether you’re mid-level, senior, or leading teams already, you contribute positively to engineering culture, support others, and help raise the bar for those around you. You align with our values and engineering principles – rooted in autonomy, accountability, pragmatism, and building things that genuinely improve people’s lives.

What the job involves

You’ll join a cross-functional product squad and work closely with engineers, designers, analysts, and product partners to build features that improve our users’ financial health. You’ll shape the direction of upcoming work, break down problems with your team, and help drive projects from early discovery all the way to shipped impact. Day-to-day, you’ll work across our backend and product systems – much of which runs in Ruby today – but you don’t need Ruby experience to thrive here.

You’ll build and evolve APIs, data models, and business logic; contribute to testing, observability, and experimentation; and help us continuously improve developer experience and product quality. Along the way, you’ll mentor others at your level (mid, senior, or beyond), share knowledge generously, and contribute to a team culture where engineers grow quickly and have real influence.

A few examples of the work our engineers shipped recently:

• Building a secured credit card
• Launching new budgeting and financial insight features
• Running subscription and pricing experiments

Cleo is built as a Ruby on Rails monolith with a single React Native app frontend, utilising TypeScript. We also leverage Python for machine learning services and PostgreSQL for our database, all hosted on AWS. Our CI/CD pipeline is fully automated, with production deployments happening on every merge via Heroku. Our backend engineers deploy multiple times a week, and we release our frontend app to Google and Apple for review at least once a week.

We’re also actively working towards a more modular architecture, focusing on separating concerns to achieve all the benefits of microservices within a monolith, while progressively refactoring our code as we build new features. Everyone in the engineering team contributes to driving our technical strategy; voices & ideas from all levels are valued: we are all owners at Cleo.