Sergiusz Jańczura

Sergiusz Jańczura

Java Developer Poznań

About me

I am a Java Developer with many years of experience in building and maintaining complex backend applications. I currently work at Hummerce (formerly Best.net), where I am responsible for developing a large-scale e-commerce platform powering multiple online shops across different markets. My work involves designing scalable solutions, optimizing performance, and integrating with external systems — including ERP/CRM platforms, payment providers, and marketing tools.

In my free time, I enjoy playing computer games, swimming, and keeping up with the latest tech trends. I'm passionate about creating stable, well-optimized systems that meet the needs of rapidly growing businesses. I also like to explore lower-level programming — currently learning Rust.

Experience

Java Developer @ Hummerce 03.2020 — Current
Tester @ Hummerce 10.2019 — 03.2020
Game Tester/Designer @ FabrykaGier 07.2018

Skills

Backend & Core

Java Spring Framework Hibernate / JPA PostgreSQL Maven / Gradle RESTful APIs

DevOps & Tools

Git Docker Jenkins Gerrit Burp Suite Postman

Other Languages

JavaScript HTML / CSS Python Rust CheatEngine
Polish (native) English (B2)

Education

Master of Computer Science Adam Mickiewicz University 2020 — 2021
Bachelor of Computer Science Adam Mickiewicz University 2013 — 2019