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

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 • 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 • 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 benefit