Senior Backend Engineer (B2B - Warsaw)

Senior Backend Engineer (London) Contract: B2B 25–40 k PLN net / month + ESOPs About Fresha Fresha is the leading AI-powered operating system for the global beauty and wellness industry, giving businesses everything they need to run smarter, grow faster and build stronger client relationships. In May 2026, Fresha secured an $80M growth investment from KKR at a valuation of $1B, officially reaching unicorn status and bringing total funding raised to $285M. Already profitable, Fresha is using this investment to accelerate global expansion and drive the next generation of AI and product innovation. Today, Fresha operates at global scale, with offices across Europe, North America, the Middle East and Asia Pacific. Our platform is trusted by 130,000+ beauty and wellness businesses across 120 countries, with more than 1.5 billion appointments booked to date. Our mission is simple: help beauty and wellness businesses grow by giving them the technology they need to attract clients, manage their operations and run their business in one place. We’re continuing to scale rapidly across markets, teams and products, making this an exciting time to join us. Role Overview Senior Backend Engineer | 11th floor, Rondo 1, 00-124 Warsaw, Poland | Four days in office, Wednesdays remote You'll join a cross-functional product team and report to its Team Lead. You'll design and build the backend services behind Fresha's booking, point of sale and payments platform, and work with engineers in other teams when a change reaches beyond your own. We work on a short feedback loop. Your change usually reaches production the same day you write it, behind a feature flag. The team that builds a service looks after it, including a shared on-call rota. We're also changing how engineering gets done here. Every engineer gets Claude, Codex or Cursor from day one, and people build their own agent workflows rather than being handed one. It isn't finished, and you'd be helping to shape it rather than inheriting it. We look for engineers who know how to break work up, how to review what comes back, and how to stand behind the result. What You'll Do Own features end to end: Design it, build it, test it, ship it, and look after it once it's live.Ship most days: Your change goes out behind a feature flag, usually the same day you write it. CI/CD handles the rollout. You watch the dashboards and roll back if it looks wrong.Work across services: Most features touch more than one repo. You'll plan and ship changes across several services at once.Work with the rest of the team: Product, Design, Frontend, Infrastructure and Mobile, from the first conversation through to release.Keep things healthy: Find the bottlenecks, fix the bugs, and keep an eye on performance and quality.Have a say in how we build: Our architecture and our engineering practices aren't fixed. We expect senior engineers to push on both. Our backend stack: services written in Ruby, Elixir and TypeScript behind a federated GraphQL layer. Kafka for events, gRPC or JSON for synchronous calls, Postgres, and everything running in Kubernetes. Domain-driven design is at the heart of how we work: we build fast, but we think about the bounded context first. We're partway through breaking our Ruby/Elixir monoliths into services. The rest of the platform: our web frontend is React and TypeScript on a custom design system, talking to the services through the same federated GraphQL layer. Our mobile apps are native, Swift on iOS and Kotlin on Android. You don't need either on day one, but you will work across them as the work requires. What We're Looking For Experience: 5+ years building and running backend services in production.Correctness: You think about what happens when a request arrives twice, a downstream call times out halfway through, or two things update the same record at once. You design for it rather than finding out later.Distributed systems: You've built and run services at scale, and you know how they fail.Event-driven architecture: You've designed systems around asynchronous events, not just request and response. Kafka or equivalent.Comfortable close to production: You're at ease shipping behind flags and watching a change land. You know what to instrument before a rollout and what to watch afterwards.AI in your workflow: You use AI coding tools day to day and have a clear view of where they help and where they don't. You're happy building your own workflow rather than waiting for one, and you review what comes back before it ships.Languages: Strong in at least one backend language. We don't expect Ruby or Elixir on day one, but we do expect you to pick things up fast.Pragmatic: You care about the right tool for the job more than any particular stack, and you've worked in more than one style of language.Curious: You like getting deep into a domain, and you're willing to get into the weeds.Willing to broaden: Frontend or native mobile experience is a bonus rather than a requirement, but we do expect engineers to pick up what a piece of work needs. At Fresha, we value passion and potential as much as specific skills. If you're enthusiastic and eager to learn, we encourage you to apply, even if you don't meet every listed requirement. Your Opportunity at Fresha Scale: Around 1 million bookings a day across 120 countries, and the payments that go with them, running on a platform we're breaking out of its monoliths while it serves traffic.Speed: We release daily, 500+ deploys a day, with not much standing between your branch and your users.Ownership: The tooling, data and permissions to run what you build, and a say in the technical direction of your area.Room to broaden: When you move into the frontend or mobile side, you get the time and support to learn it rather than being thrown at it. Interview Process Screen Stage - Video call with a member of the Talent Team (30min)1st Stage - Technical video/in-person interview (90min)2nd Stage - Practical coding session plus system design and architecture (up to 2 hrs)Final Stage - Video interview with Head of Engineering / VP of Engineering (60min) No take-home exercise. We aim to finish the whole process and give feedback within 4 weeks. Inclusive workforce At Fresha, we are creating a culture where individuals of all backgrounds feel comfortable. We want all Fresha people to feel included and truly empowered to contribute fully to our vision and goals. Everyone who applies will receive fair consideration for employment. We do not discriminate based on race, colour, religion, sex, sexual orientation, age, marital status, gender identity, national origin, disability, or any other applicable legally protected characteristics in the location in which the candidate is applying. If you have any accessibility requirements that would make you more comfortable during the interview process and/or once you join, please let us know so that we can support you. We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us