Senior Full Stack Engineer — TypeScript / Next.js (100%, m/f/d)

Your missionYou are the architect and builder of the customer-facing side of the LEASETEQ platform in Berlin, and the owner of our German market on it. You design the digital application journey and the portals that carry real customers, dealers and operations teams at production scale, and you make sure German credit rules, compliance requirements and dealer flows are represented correctly in a platform that also serves Switzerland and Austria. You work in a small, senior team where your decisions have direct product impact, and you naturally bring AI tooling into your daily engineering workflow without being asked. What you will do Own the German market on our customer-facing platform: credit and compliance requirements, dealer flows, German copy, and the acceptance criteria that make them verifiableDesign and build the digital application journey — multi-step forms, validation, resumable state, document upload, KYC steps and the unhappy paths users actually hitBuild and maintain the customer, dealer and operations portals, including the operations board and the logic that decides where a case belongsWrite the use-case and API layers behind the journey to our clean-architecture standard — this is a full-stack role, not a UI roleOwn field-level mapping into the CRM and the Flowable-based process engine — beneficial ownership, source of funds, origin of income, additional persons — where a wrong key is a compliance defect, not a cosmetic oneAuthor specification-driven change proposals, and act as the named human approver for journey and mapping changes in the German marketGrow end-to-end test coverage on the critical journeys: coverage is what licenses autonomous agent work in a moduleWork with our Berlin backend team on the seam between the orchestration core and the customer-facing platform, and with our Jakarta platform engineers who own the journey across all three marketsCommunicate clearly in German and English with engineering peers and business stakeholders Your profile6+ years of full-stack TypeScript engineering, with recent production work in React and Next.js App Router — server components, server actions and route handlers, with a clear grasp of what runs where — is mandatoryFintech experience is mandatory: production work on a regulated financial product — leasing, lending, banking, payments or insurance — where money moved and a regulator could ask whyProven ownership of a complex multi-step onboarding or application flow is mandatory: validation strategy, partial persistence and resumption, conditional branching by market or product, document uploadReal backend capability: use cases, repository implementations, API handlers and PostgreSQL / Prisma queries — roughly a 60/40 split toward the frontend, not 90/10State and data-fetching maturity (Zustand or equivalent, TanStack Query) and confident use of form and schema tooling (Formik or React Hook Form with Zod), including server-side validation parityEnd-to-end testing with Playwright or Cypress on flows that are slow, stateful and integration-dependentAI-first engineering mindset: daily use of coding assistants and agents on production work, and the ability to write a change specification precise enough that an agent implements it correctly and a reviewer can verify that it didWorking understanding of the German regulatory environment for consumer credit or asset finance — BaFin-supervised context, AML/KYC obligations, consumer-credit disclosure — is a strong plusInternationalisation as a habit — no hard-coded strings, and awareness of what four locales do to layout and copyFluent German and English Why us?Founding-team-level ownership of our customer-facing platform and of the German market on itDirect collaboration with the CTO and the founders, including regular visits to our Swiss headquartersA genuinely AI-first process, not a slogan: specification-driven delivery where agents execute approved changes and humans own scope, architecture, regulatory and r