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

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.

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