Senior Ruby on Rails Developer

About Momentum:Momentum is a Wrocław-based team building software for healthcare companies worldwide. For years we've helped HealthTech startups and scaleups turn ideas into compliant, production-ready products. Now we're also building our own, in wearables and medical data integration, and part of that work is open source.We work AI-first. AI is part of our everyday work, in development and in delivery. We keep testing new tools, agents and workflows, and when we find a better way to build, we change how we work.Curious how we work? See what we're building: Open Wearables on GitHub.Role overview:We're looking for a Senior Ruby on Rails Developer to join a project for a US-based HealthTech client.You'll write and review code, contribute to architecture decisions, optimize performance and care about code quality, working closely with PMs, designers and other developers. You'll use AI every day to move faster, and you'll be the one who makes sure the code is actually correct, secure and maintainable before it gets merged. 'AI generated it' isn't done. In healthcare, a subtle bug or a missed edge case costs more than time.What you'll doDesign and build web applications in Ruby on Rails, including relational database designWork with cross-functional teams to define, design and ship new featuresWrite automated tests that cover edge cases and overall reliabilityFix bugs and improve performanceReview code with the same standards, whether a person or AI wrote itHelp define and improve internal standards for maintainability and styleTalk directly with the client when needed: clarify requirements, discuss technical solutions and present your workTest new tools and workflows, and share what works with the teamWhat you'll need5+ years of commercial experience with Ruby and Ruby on RailsStrong knowledge of relational databases (e.g. PostgreSQL), plus practical experience with non-relational databases, caching and message brokersExperience with client communication (e.g. REST API, WebSockets) and authentication methods (e.g. JWT, cookie-based auth, OAuth)Experience with CI/CD, deployment tools, Docker and GitPractical knowledge of design patterns and SOLID principlesExperience writing and maintaining automated tests with RSpec or similar frameworksAbility to contribute to architecture based on business, functional and non-functional requirements, with an understanding of scalabilityDaily use of AI tools and the ability to critically review AI-generated codeLove for code review, both giving and receiving itFluent English and confidence talking directly with clients during calls, demos or technical discussionsFluent Polish, our main language of internal communicationInterest in HealthTech and in projects where quality, security and compliance really matterNice to haveExperience with a JavaScript framework like Vue or ReactExperience with AWS or a similar platformExperience with web servers (e.g. Nginx)HealthTech or pharmacy experience: HIPAA, e-prescribing, insurance, FHIRExperience working embedded with a client, in consulting, as an FDE or in a startup where you wore several hatsThis role probably isn't for you if:you prefer to treat a ticket as finished once the code runs, rather than when it's tested, reviewed and something you'd be comfortable maintaining a year from now,you prefer a stack and workflow that stay the same for years. We regularly test new tools and approaches, and when we find a better way to build, we adopt it,you'd rather someone else took responsibility for what gets merged. Here, AI can write a first draft, but you're the one who signs it off.What We Value:Clarity in focus and dedication to building digital products that elevate healthcare and improve quality of life.Flair to face challenges with boldness, creativity, and a proactive mindset.Grit to take ownership, stay ambitious, and deliver refined, high-quality solutions.Impact through meaningful innovation that makes pioneering medical discoveries accessible and human-centered.Ability to collaborate efficiently in teams of technical and non-technical individuals, and comfortable working in a dynamic environment with evolving objectives and iteration with users.What we offer:AI tools like Claude and Gemini, with real influence on how we use AI and space to test new tools and workflowsFlexible working hoursModern office in the heart of WrocławOffice visits reimbursed for remote team members, both required and optionalPrivate healthcare and Multisport cardGroup insurance for you and your loved ones (optional)Worksmile cafeteria with hundreds of benefits to choose fromMicrofunds for team events and skill developmentThinking of applying? Awesome! How we recruit:We keep our process short and to the point:Intro call (20 min): a quick chat about your experience and what you're looking for.Recruitment task: a short task, with three working days to complete it.Technical interview (45-60 min): a deeper conversation with a senior team member, including a walkthrough of your solution.Meeting with our CTO (15 min): a chance to hear about where Momentum is heading and ask your own questions.Decision and feedback: we'll get back to you with our decision and detailed feedback.