Full-Stack Engineer

We know how to attract and retain hosts willing to rent their spare rooms on Colette.

• We consistently meet the demand of young people looking for housing.
• Our matching process is proven, and active members rate our house-sharing service 4.5/5.
• We know how to build and retain a club of activities that seniors love.

Where we're going

• Build and grow a trusted community, online and offline.
• Deliver a world-class intergenerational house-sharing experience in France.
• Increase the number of house-sharing matches we create each month.
• Become the largest club of activities dedicated to seniors.

To get there, we're looking for an outstanding engineer, as keen and enthusiastic as we are, to help us build the product and technology that makes it possible.

Our stack

• Backend: Elixir (Phoenix), Ruby
• Frontend: React with Next.js and Remix, TypeScript
• Mobile: Flutter
• APIs: GraphQL and REST
• Data & payments: PostgreSQL, Stripe
• Infra & delivery: Docker, Fly.io, Neon, AWS, Google Cloud, GitHub
• AI: frontier models from Anthropic, OpenAI, and Google; Claude as everyday collaborator, plus AI-powered features in the product

Your role

As a full-stack engineer, you will own features end-to-end - from the backend architecture all the way to the interfaces our members use every day. You'll work closely with product, design, and operations to ship solutions that are simple, reliable, and fast. You'll also work hand-in-hand with frontier AI models as everyday collaborators - for coding, research, and for the AI-powered features we're building into our products. To be clear: this is not vibe-coding. You're expected to deeply understand every line that ships, review AI output with the same rigor you'd apply to your own code, and own the outcome.

What you'll do

• Partner with product, operations, and business teams to understand problems deeply and design the best solutions - not just the obvious ones.
• Shape the architecture of our backend (Elixir) and the APIs (GraphQL and REST) that power our web and mobile clients.
• Build the user-facing experiences on top of those APIs with React (Next.js, Remix), with care for performance, accessibility, and polish.
• Use frontier AI models to move faster and smarter, and design AI-powered features that genuinely improve our members' experience.
• Ship high-quality, well-tested code that other engineers enjoy working with.
• Improve our infrastructure (Fly.io, Neon, AWS, Google Cloud) and automate the boring parts so the team can move faster.
• Maintain clear technical documentation and own the quality, scope, and delivery of your projects.
• Keep pushing the codebase forward: challenge the status quo, pay down tech debt, and bring in new ideas.
• Own our communication (email, push notifications, and SMS) integrations end-to-end - the backbone of how we communicate with members, hosts, and candidates.

What you bring5+ years of engineering experience across backend and frontend, including at least 1 year shipping and operating high-traffic production apps.Comfort building modern web frontends with React and a framework such as Next.js or Remix, with TypeScript, and a good sense for UX details.Backend experience in Elixir (and/or Ruby), and solid grounding in web technologies, distributed systems, and software design.Fluency with SQL, REST, and GraphQL, and hands-on experience with PostgreSQL, Stripe, and Docker.A good eye for system design and API ergonomics - you understand that better APIs make better frontends.Working knowledge of cloud platforms (Fly.io, Neon, AWS, or Google Cloud) and CI/CD tooling (e.g., GitHub).An appetite for mobile technologies such as Flutter (bonus if you've already shipped a mobile app).Fluency with frontier AI tools (Claude, Cursor, Codex, or similar) as part of your day-to-day engineering workflow.The ability to move quickly in a fast-paced environment without sacrificing quality or clarity.Native French speaker, with excellent written and spoken English., * 5+ years of engineering experience across backend and frontend, including at least 1 year shipping and operating high-traffic production apps.

• Comfort building modern web frontends with React and a framework such as Next.js or Remix, with TypeScript, and a good sense for UX details.
• Backend experience in Elixir (and/or Ruby), and solid grounding in web technologies, distributed systems, and software design.
• Fluency with SQL, REST, and GraphQL, and hands-on experience with PostgreSQL, Stripe, and Docker.
• A good eye for system design and API ergonomics - you understand that better APIs make better frontends.
• Working knowledge of cloud platforms (Fly.io, Neon, AWS, or Google Cloud) and CI/CD tooling (e.g., GitHub).
• An appetite for mobile technologies such as Flutter (bonus if you've already shipped a mobile app).
• Fluency with frontier AI tools (Claude, Cursor, Codex, or similar) as part of your day-to-day engineering workflow.
• The ability to move quickly in a fast-paced environment without sacrificing quality or clarity.
• Native French speaker, with excellent written and spoken English.

Colette (www.colette.club and www.colette-cohabitation.com) is on a mission to help people age well and make cities more livable. We do this through two complementary products: an intergenerational house-sharing service that matches students and young professionals with seniors who have a spare room, and a club of online and offline activities dedicated to seniors. In May 2025, Colette was acquired by Renée Costes, France's leading specialist in senior living (including viager - life annuity real estate). The partnership accelerates our mission and gives us the scale to reach millions of seniors across France. Why this matters: by 2035, roughly one French person in three - around 22 million people - will be over 60 (INSEE), and 90% of them want to age at home. Loneliness has the same negative health impact as smoking 15 cigarettes a day, and housing affordability has become a crisis for young people in big cities (61% of 18-34-year-olds report struggling to find housing). Bringing generations together solves both problems at once. And on the activities side, keeping seniors physically and mentally active is one of the most reliable ways to preserve their health, independence, and joy - which is exactly what our club is designed to do.