Marek Żarnowski
Software Engineer at j-labs software specialists
Krakow, Lesser Poland Voivodeship
Summary
🤩
Rockstar🎓
Top SchoolMarek Żarnowski is a senior software engineer with 12 years’ experience building backend systems, currently working on an algorithmic trading platform in Krakow. He has deep Scala and Java expertise, contributing to high-profile open-source projects like Metals (Scala language server) and Bloop (fast Scala build server), where he implemented Debug Adapter Protocol support, code-folding, and improved breakpoint/debug handling. Marek has led small teams through onboarding and process changes, favoring pragmatic, lean workflows and pair programming to accelerate knowledge transfer. His background spans data engineering on Spark/Hadoop, tooling for IDEs, and designing durable persistence layers—skills forged by shipping long-lived systems and improving developer tooling. Colleagues know him for turning operational pain points into shareable solutions, such as an IntelliJ plugin testing framework and modular CQRS refactors that stood the test of time.
12 years of coding experience
9 years of employment as a software developer
AGH University
Stackoverflow
1reputation
0reached
0answers
0questions
Github Skills (13)
scala10
compiler10
debugging10
debug10
build-server10
build-tools10
language-server10
build-system10
code-folding10
testing10
developer-tools9
ls9
scalatest8
Programming languages (6)
Github contributions (5)
scalameta/metals
Apr 2019 - Jan 2020
Scala language server with rich IDE features 🚀
Role in this project:
Back-end Developer
Back-end DeveloperContributions:129 commits, 40 PRs, 13 pushes in 9 months
Contributions summary:Marek primarily focused on enhancing the Scala language server functionality within the Metals project. Their contributions involved the implementation of code folding features, specifically for for-loops, partial function cases, and comments. Furthermore, they modified the debug adapter and improved the handling of breakpoints to enhance the debugging experience. The user made several improvements related to code formatting and test suite structure.
atom-pluginscalametavscodeide-featuresscala
scalacenter/bloop
Jan 2019 - Dec 2019
Bloop is a build server and CLI tool to compile, test and run Scala fast from any editor or build tool.
Role in this project:Backend Developer
Backend DeveloperContributions:4 reviews, 86 commits, 16 PRs in 10 months
Contributions summary:Marek primarily contributed to the build server and CLI tool named Bloop, by adding support for Scala main and test classes requests. The user also implemented changes to the debug session by including the start endpoint. Furthermore, the user extracted connection handling and made modifications to the internal structure of the test suites.
build-serverproductivitycompilation-servercompiledeveloper-tools
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