Senior Software Engineer building systems that scale

I specialize in the complex intersection of money, compliance and legacy code.

Over nearly two decades, I've architected and transformed systems where failure isn't an option:

  • Payment Infrastructure — Built PCI DSS Level 1 compliant gateway from scratch. Every transaction matters when you're handling money.
  • Financial Platforms — Deep experience with invoicing, accounting, and reconciliation systems. Insurtech modernization. Systems that auditors love.
  • High-Scale Commerce — Ticket selling platforms handling traffic spikes and inventory conflicts. Real-time, high-stakes, zero-tolerance for errors.
Szymon Fiedler

How I deliver impact

  • Architecture & Design — Domain-Driven Design practitioner, Rails Event Store maintainer, event sourcing expert. I build systems that capture business complexity while remaining maintainable.
  • Legacy Transformation — With Arkency since 2014, I've modernized systems others deemed "untouchable." Gradual, safe migrations that preserve business continuity.
  • Technical Leadership — 15 years training and developing teams. wroclove.rb conference organizer. I multiply impact through others.
  • Remote Excellence — Delivering critical systems remotely since 2014. Location independent, results dependent.

The problem I solve

  • Payments systems that need to scale but can't compromise security
  • Legacy Rails applications blocking business growth
  • Financial platforms requiring both modernization and compliance
  • Technical debt that's become a business risk
  • Teams needing technical direction through complex transformations

My approach

I think in systems, not features. When I see a bug, I look for the pattern. When I design a solution, I consider the next five years. When I write code, I think about the engineer who'll maintain it.

Experience has taught me that the hardest problems are rarely purely technical — they're at the intersection of technology, business domains, and human systems. That's where I operate best.