Principal Software Engineer - Fintech Platform (m/f/n)

Employment: Full-time Experience level: Mid-Senior Level Job Description As Principal Software Engineer, you'll work directly with the Head of FinTech Engineering and business leadership, translating critical business goals - new product lines, regulatory deadlines, growth targets - into architecture decisions and roadmap input. You'll be the final word on cross-domain technical questions that no single team or Staff Engineer can resolve alone. → Hybrid working model: preferably 1 day per week in the Warsaw or Cracow office .   Responsibilities: Serve as the single cross-domain technical authority, arbitrating architecture decisions across Payments Core, Merchant, and Consumer platform areas Partner directly with the Head of Engineering and business leadership to turn business strategy into technical roadmap input Author Architecture Decision Records (ADRs) and RFCs for organisation-wide decisions, with reasoning accessible to both engineers and business stakeholders Own the agentic engineering harness at an organisational level — design, instrument, and continuously improve AI-assisted engineering workflows based on real production data Identify and drive the adoption or deprecation of patterns across all teams, building the case and sequencing change without direct authority Mentor Staff Engineers and Engineering Managers on architecture craft, technical communication, and agentic tooling Qualifications 10+ years in software engineering, including 5+ years in cross-team technical leadership or architecture authority 5+ years designing distributed payments or fintech systems 3+ years of agentic/LLM engineering in production — shipped systems, not theoretical patterns Deep knowledge of distributed systems architecture: event sourcing, CQRS, domain events, saga pattern Experience designing APIs at an organisational boundary level — REST, async, and event-based contracts Strong grasp of database trade-offs (relational, time-series, document, ledger-style) and cloud architecture evaluation (AWS/GCP/Azure) at organisation scale Hands-on experience with multi-agent orchestration, tool-use patterns, context management, and evaluation harnesses for AI-assisted engineering workflows Excellent technical writing for mixed audiences — ADRs and RFCs that work for engineers and business leadership alike English proficiency at B2 or above University degree in Computer Science, IT, or a related field Nice to have:  3+ years in platform or internal developer tooling engineering 1+ years of agentic/LLM system design experience PCI DSS / PSD2 architecture compliance experience from the design phase BNPL or lending domain architecture experience Open-source contributions or external technical publishing Experience building or scaling an internal developer platform Formal mentorship of Staff-level or EM-track engineers 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 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.