Principal Software Engineer

Quick Facts

• Role: Principal Software Engineer (Principal Platform Engineer)

• Type: Individual contributor (no people management)

• Work mode: Hybrid (3 days in Kraków office) or Remote (B2B)

Description

You will help shape the technical future of the platform by owning its architecture and backend engineering standards. The role combines hands-on ownership of the hardest performance and integration problems with the ability to multiply impact through mentorship, design reviews, and clear engineering standards. You will partner with the Director of Software Engineering across the organization and contribute strong technical judgment in a high-change environment.

Responsibilities

• Own the architecture and technical direction of the platform’s core backend

• Tackle performance bottlenecks, complex integrations, and architectural evolution

• Define and evolve backend engineering standards across all teams

• Lead design reviews and author RFCs/ADRs for high-impact decisions

• Partner early with engineering leadership and Product on technical feasibility and tradeoffs

• Mentor senior engineers via code reviews, architecture workshops, pair programming, and tech talks

• Raise the quality bar across the backend through example and clear standards

Requirements

• 8+ years of backend engineering experience

• Deep, proven mastery of C# and modern .NET

• Track record operating successfully as Staff Engineer, Principal Engineer, or Senior Tech Lead

• Proven experience architecting, building, and owning large complex systems end-to-end (monolithic and distributed)

• Expert SQL and database design skills, including diagnosing slow queries in production and designing load-ready schemas

• Deep expertise with Entity Framework, including performance tradeoffs and data access strategy

• Strong architectural judgment with practical application of DDD and clean architecture

• Quality mindset: test automation strategy and clear standards for what “done” means

• Strong English communication for explaining tradeoffs, mentoring, leading code reviews, and facilitating architecture discussions

• Hands-on experience with AI coding tools such as Cursor and Claude Code

Benefits

• Real authority and close collaboration with the CPO and Director of Development

• Work on impactful, advanced customer programs with real consequences

• High-bar team environment with experienced engineers and leaders

• AI built into the platform foundation

• Hybrid schedule (3 days in Kraków office), comprehensive healthcare with life insurance, and a Multisport Card