Staff Software Engineer, Frontend - Fintech Platform (m/f/n)

Employment: Full-time Experience level: Mid-Senior Level Job Description InPost's FinTech Platform team is looking for a Staff Engineer to define the technical direction for one of our platform areas - Payments Core, Merchant, or Consumer. You'll multiply team output through architecture clarity, engineering standards, and cross-team technical leadership, while helping evolve our agentic engineering harness in a data-driven way. You'll own the evolution of fundamental technology decisions across your area - ensuring they're sound, defensible, and viable for the long term - and act as the technical throughline between engineering teams, product strategy, and the organisation's wider architecture standards. → Hybrid working model: preferably 1 day per week in the Warsaw or Cracow office . Responsibilities: Define and maintain frontend architecture across the area: component architecture, design-system boundaries, micro-frontend patterns, client-side state management, and performance budgets across multiple teams Author Architecture Decision Records (ADRs) and RFCs for frontend decisions, facilitating technical decision-making across teams with documented reasoning and clear trade-off analysis Evaluate and decide on fundamental frontend technology trade-offs: framework and library selection, build tooling, rendering strategy (SSR / CSR / ISR), and accessibility standards Own the evolution of the agentic development harness for frontend workflows — instrument it, measure adoption and friction, and drive improvements with data Drive org-wide technical change: identify frontend patterns and design-system components to adopt or deprecate broadly, build the case, and see adoption through across teams without direct authority Provide technical input into product strategy; mentor Staff-track engineers through design reviews, pairing, and technical writing feedback Qualifications 8+ years in software engineering, including 2+ years in cross-team technical leadership or architecture authority 3+ years building customer-facing or merchant-facing products in payments or fintech Expert-level experience with a modern frontend framework (e.g. React) and TypeScript at scale Design-system and component-architecture experience across multiple teams or products Micro-frontend architecture and client-side state management patterns Performance engineering expertise — Core Web Vitals, bundle optimisation, and rendering-strategy trade-offs (SSR / CSR / ISR) Accessibility standards (WCAG) built into architecture, not bolted on API-consumption patterns: REST, GraphQL, async, and event-based contracts Experience designing or evolving an agentic engineering harness for frontend workflows — instrumentation, adoption measurement, iteration Excellent technical writing — ADRs, RFCs, and design docs for multiple audiences English proficiency at B2 or above University degree in Computer Science, IT, or a related field Nice to have: 2+ years in platform or internal developer tooling engineering 1+ years of agentic/LLM system design experience 2+ years in BNPL or lending domain product experience Mobile app architecture (e.g. React Native) alongside web Real-time UI patterns (WebSockets, streaming updates) Internationalisation / localisation architecture at scale Open-source contributions or technical publishing Polish language skills Additional Information Opportunity to work in a  diverse ,  international , and  cross-functional environment,  along with leading  experts .  You work and learn from a senior leader and their leadership team, expanding your experience and exposure in the e-commerce and logistics industries.   InPost is a growing company that offers its people an increasing number of opportunities in several locations in Europe.  Fulfilling careers with a  range of benefits  for people and investing in providing  training opportunities  for their development.  You will feel a part of the InPost community that makes an impact on sustainability, convenient deliveries, and the circular economy every day.  Excellent working environment and flexible hours We offer B2B type of contract   Company Description InPost Pay is building its own fintech platform from the ground up. It’s a large-scale, international initiative where engineers will have the opportunity to shape the architecture, build core fintech components, and create solutions designed to operate at InPost’s scale. We’re building a lean, highly effective engineering organization in Poland, with AI-native engineering at its core . We’re looking for strong engineers who are comfortable with agentic engineering, from experienced professionals building complex systems and engineering tooling to a new generation of engineers who have embraced AI-driven development from the start of their careers.