Mateusz Kozak
Senior BI Analyst at Żabka Polska
Greater Poland Voivodeship
Summary
🤩
Rockstar🎓
Top SchoolMateusz Kozak is a Senior BI Analyst with five years of experience turning complex datasets into actionable business strategies across retail and finance. Based in Greater Poland, he has driven measurable efficiency gains through automation—halving reporting times with VBA and cutting process durations by up to 90%—and built predictive models to lift promotional effectiveness and user engagement. At Żabka he led KPI design, A/B testing and AI/ML-driven user insights to optimize app features and marketing. Earlier roles in banking and e-commerce honed his skills in SQL, Python, Oracle, GCP and Tableau for robust reporting and budgeting. Unusually for a BI professional, he also contributes low-level backend code to major open-source projects like dotnet/runtime, having implemented and optimized SIMD intrinsics in the Mono JIT, demonstrating both analytical rigor and systems-level programming chops.
5 years of coding experience
1 year of employment as a software developer
Magister (Mgr), Finanse i rachunkowość, Magister (Mgr), Finanse i rachunkowość at Poznan University of Economics And BusinessLicencjat, Finanse i rachunkowość, Licencjat, Finanse i rachunkowość at Uniwersytet Ekonomiczny w Poznaniu
Polish, English
Github Skills (6)
c1710
simd10
intrinsics10
c1110
vectorization10
llvm9
Programming languages (5)
Github contributions (5)
dotnet/runtime
Sep 2022 - Nov 2022
.NET is a cross-platform runtime for cloud, mobile, desktop, and IoT apps.
Role in this project:
Backend Developer
Backend DeveloperContributions:220 reviews, 14 commits, 202 PRs in 2 months
Contributions summary:Mateusz primarily contributed to the Mono runtime's Mono JIT compiler, focusing on implementing and optimizing SIMD (Single Instruction, Multiple Data) intrinsics for the AMD64 architecture. They added intrinsics for vector operations like Floor, Ceiling, SQRT, Sum, ConditionalSelect, AndNot, Negate, OnesComplement, Dot, and Abs. Additionally, they refactored existing code and fixed bugs related to these intrinsics. This work involved modifications to the mini-JIT and mini-llvm components within the runtime.
dotnetruntimelinuxcsharpxamarin
matouskozak/performance
Nov 2022 - Apr 2025
This repo contains benchmarks used for testing the performance of all .NET Runtimes
Contributions:37 pushes, 9 branches in 2 years 5 months
dotnetbenchmarkingruntimestestingbenchmark
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