Andrzej Kobyliński

Full-stack engineer · Warsaw, Poland · 10+ years

How I work

Architectures: DDD · hexagonal · event-driven · CQRS
Practice: TDD by default · integration tests on real dependencies, not mocks
Mindset: Observability is part of the deliverable, not a separate phase

Tools

Backend: Kotlin (Coroutines, Ktor, Exposed) · Java · Spring Boot · Postgres · Apache Kafka · Resilience4j · ArchUnit
Frontend: TypeScript · React · Next.js · Astro · Vite · Tailwind · Serwist
Ops: Docker · Kubernetes · AWS EKS · Helm · GitHub Actions · GitLab CI

Domains

Payments and e-commerce · insurance · financial settlement · Polish-tax-aware fintech. The recurring shape: complex domain rules, money in motion, downstream systems that mustn't go out of sync.

Why I build solo too

Beyond commercial work I build products I'd use myself — kryptopodatki.pl, ariettacars.com, and tooling for the way I work like nozbe-classic-mcp. My bar: if I wouldn't use it, I don't ship.

What I'm into

AI agents and agentic coding — not as a side topic, but as how I build now. MCP servers, custom skills, Claude Code as a daily driver.

Backend craft with strong invariants. Kotlin + Exposed + transactional outbox patterns for event-driven systems where you can't afford message loss. Contributor to softwaremill/okapi; published on VirtusLab blog.

Experience

Senior Kotlin Developer

SoftwareMill Remote

2025–2026

B2B SaaS for the German motor-fleet insurance market — microservices in Kotlin/Spring Boot on Kubernetes.

Built backend pipeline for regulatory data exchange between insurers
Designed feature-flag-gated migration framework for live data re-processing
Maintained ArchUnit-enforced hexagonal boundaries across services

Kotlin
Spring Boot
Kubernetes (EKS)
Postgres
Kafka
Testcontainers
Helm

Senior Developer

BlueSoft Remote

2021–2024

E-commerce platform for a major Polish retailer — payments, marketplace, inventory.

Co-architected payment orchestration over 6+ external providers (cards, BLIK, BNPL, bank transfer)
Built event-driven inventory pipeline replacing legacy SQL procedures
Owned end-to-end payment authorization flows under strict hexagonal architecture

Java
Kotlin
Spring Boot
Apache Kafka
ActiveMQ
DDD
Hexagonal
Postgres
Kubernetes

Developer → Senior → Team Lead

Sollers Consulting On-site

2016–2020

Insurance configuration platforms for global carriers.

Led monolith → modular monolith refactor (Maven modules)
Drove DDD adoption across teams via workshops and pilot domains
Implemented CQRS, SSE features with feature-flag-gated rollout

Java
DDD
CQRS
Maven
Docker
Spring

Education

BSc, Computer Science

Warsaw University of Technology

2012–2016

Specialization: Software Engineering.

Selected trainings

Smart Testing2023
Legacy Fighter — Bottega2021
DDD Implementation, Pragmatic Refactoring with DDD — Bottega2020
Designing Next-Gen Architecture2019

Selected work

See Products for the full list.