Senior Software Engineer - Ruby on Rails (f/m/d)

Are you ready to change the market? At PAIR Finance we're building the AI-driven platform that's redefining debt collection across Europe. We're looking for a senior software engineer who takes ownership end-to-end, is comfortable being the technical driver of a well-defined scope, and is energized by learning a deep, high-stakes domain: the legal processes around In-Court and After-Court debt collection. Your Responsibilities: Own a clear scope end-to-e nd: take initiative from idea to production largely independently, and lead within your team (T-shaped: you go deep on your slice, and pair with one other developer) Design, build, and run POCs quickly to de-risk decisions before committing to a full build Develop, optimize, and maintain our core backend applications and services Work on high-level architecture to ensure scalability, performance, availability, and security Go deep on the In-Court/After-Court domain (the legal and procedural knowledge behind our collection processes is a core part of the job, not a side detail) Collaborate closely with product to shape the roadmap and unlock further company growth Work AI-augmented: you already use (or are ready to adopt) tools like Claude Code as part of how you build, review, and ship Help evolve and enhance our AI-based platform Stay current with industry trends and bring ideas back to the team What we're looking for: 5+ years of professional software engineering experience, including 1+ year on medium-to-large projects Strong backend experience in Ruby (Ruby on Rails) : this is our core stack, and required for the role Language-agnostic mindset: you pick the right tool for the job (hands-on experience with Go and/or Python is a big plus) Proven ability to work independently: scope, drive, and deliver a project with minimal hand-holding Experience with TDD and CI/CD A track record of writing clean, maintainable backend code and solid infrastructure Comfortable in an Agile environment ( Scrum, Kanban) Genuine interest in working with, and building on top of, AI-based technologies Solid English communication skills Nice to have: Experience in the financial or accounting industry Frontend development experience, especially Vue.js and GraphQL knowledge Infrastructure experience: AWS, Terraform (IaC), Docker, Linux Knowledge of other backend technologies, such as Node.js, Rust, or Java Our offer for you: For this senior-level role, our salary band is €77,000 - €92,000 gross per year (based on a 40-hour work week). The exact offer will reflect your experience and qualifications We offer visa sponsorship Thriving, financially stable company Strong experienced international team to support and mentor you along the way, smooth onboarding process International team of 30+ nationalities with professionals and experts Flat hierarchy, transparent and appreciative feedback culture, monthly all hands meetings, annual feedback and evaluation cycle, regular 1-on-1s with your lead Well-structured onboarding proc