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

InPost Group is an innovative European out of home deliveries company, revolutionizing the way parcels are delivered to customers. With operations across several countries, our network of intelligent lockers provides customers with a fast, convenient, and secure delivery option. InPost Group is a publicly traded company, with a market capitalization of about $5 billion as of March 2023. With over 10,000 people worldwide, InPost Group is one of the largest out of home delivery providers in Europe, committed to providing sustainable and efficient delivery solutions to meet the evolving needs of customers in today's rapidly changing landscape.

We are a team that builds the best FMCG e-commerce in Poland. We already have over 300,000 products in our offer, we work with over 300 sellers, and our mobile application has already been downloaded by almost 1.5 million users in Poland. Due to the fact that our product consists of many elements that must work together efficiently and be managed effectively, we are looking for experienced consumer-focused (Web / Mobile App products) engineering leaders to join us in that journey - heavily influence our future platform build, improve processes and help us deliver best customer experience in the market across all types of devices.

InPost is building the FinTech platform that powers payments for one of Europe's largest logistics and e-commerce ecosystems. We're looking for a Principal Software Engineer to become our organisation-wide technical authority - someone who can arbitrate architecture decisions across Payments Core, Merchant, and Consumer domains, and who has genuinely shipped AI-assisted engineering workflows in production, not just talked about them.

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

• 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

• 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