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

InPost Pay 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 the backend technical architecture for your area: domain boundaries, event contracts, state machine patterns, data consistency models, and cross-service API design across multiple teams • Author Architecture Decision Records (ADRs) and RFCs, facilitating technical decision-making across teams with documented reasoning and clear trade-off analysis • Evaluate and decide on fundamental technology trade-offs: database selection, cloud services, message broker topology, and consistency models appropriate for financial data • Own the evolution of the agentic development harness - instrument it, measure adoption and friction, and drive improvements with data • Drive org-wide technical change: identify patterns 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