Senior Backend Engineer (Node.js / TypeScript)

We are looking for a highly experienced Senior Backend Engineer to join an innovative and fast-growing company in the fitness tech industry. You will play a key role in building and scaling the backend architecture of a cutting-edge platform used by gyms across Europe. This is an exciting opportunity to work in a startup environment where your ideas, ownership, and technical expertise will have a direct impact on the product and customers. About the Mission Your mission will be to build and evolve the platform from the ground up, leveraging the experience acquired during the Beta phase and current product usage. You will work closely with product, customers, and the engineering team to deliver a scalable, reliable, and high-performance application. Responsibilities Design and implement scalable backend architectures and server-side application logic Develop APIs, reusable libraries, and core system components Integrate with external Gym Management Software and third-party services Collaborate closely with customers to gather feedback and solve technical issues Write clean, maintainable, and well-tested code Participate in technical decisions and mentor less experienced developers Work directly with clients for product conception and training purposes Travel occasionally across Europe to better understand gym staff workflows and operational needs Contribute to building a responsive, cost-effective, and customer-centric platform Required Skills & Experience 10+ years of experience building backend systems At least 1 year of experience with Node.js and TypeScript Strong experience with SQL databases, ideally PostgreSQL Experience working with Prisma ORM Strong sense of ownership and code quality Experience writing automated tests Ability to learn quickly and adapt in a startup environment Excellent communication skills with fluent English (C1 level) Customer-focused mindset and passion for delivering outstanding user experiences Team player willing to share knowledge and mentor others Nice to Have Experience with AWS services and AWS Lambda Experience with Serverless architectures Experience building GraphQL APIs Additional European languages Passion for fitness or regular sports practice Tech Stack Node.js TypeScript PostgreSQL Prisma ORM AWS GraphQL What We Offer Salary: €50,000 – €55,000 gross/year Fully remote work Sport card / fitness benefit Private medical insurance International and collaborative environment Opportunity to shape a product from an early stage