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Jakub Zalewski
Data Scientist & ML Engineer — building models, teaching people, fixing businesses, recording bands.
I Data Science & Machine Learning
10+ years shipping production ML across AdTech, FinTech and e-commerce — from problem framing and pipelines to A/B evaluation and business impact. Full CV available for the deep lore.
Senior Software Engineer in Data Science
Oct 2025 – PresentParamount Global · Warsaw
- End-to-end ownership of a lookalike modelling pipeline for SMB advertisers across Pluto TV and Paramount+.
- Designed and productionised a LightGBM-based lookalike model (MLflow pyfunc) with custom encoder artifact management and FreeWheel ad-server log ingestion.
- Led cross-functional alignment with the Orion data platform team on schema contracts and ingestion SLAs for a unified event stream.
- Architected an A/B testing framework (user-level, geo, and PSA holdout splits) for rigorous business impact measurement.
Data Scientist
Oct 2023 – Sep 2025Adform · Warsaw
- Owned ML models for programmatic advertising targeting end-to-end — scoping, modelling, evaluation, stakeholder communication.
- Built large-scale PySpark pipelines for bidstream data processing and feature engineering.
Data Scientist / Senior Data Analyst
Oct 2019 – Sep 2023Allegro · Warsaw
- Progressed from Data Analyst to Data Scientist across Search and Delivery Experience at Poland's largest e-commerce platform.
- Owned analytical and ML deliverables for Allegro Search — A/B experiments, statistical modelling, ML-based ranking.
Senior Credit Risk (Data) Analyst
Sep 2017 – Sep 2019IPF Digital · Warsaw
- Built and owned credit risk scoring models for digital lending products across multiple European markets.
Inventory & Skills
II Teaching & Mentoring
Passing the +1 modifier forward — academic teaching plus hands-on mentorship in software design, machine learning, data science and data engineering.
Academic Teacher
Sep 2025 – PresentWSB Merito University Warsaw
- Designs and delivers courses spanning Big Data Management (PySpark, MLflow), Advanced Python for Data Science, C# Advanced Programming, Application Quality (CI/CD, E2E testing), and Web Programming.
Python Developer & Data Science Mentor
Apr 2024 – PresentFuture Collars
- Mentors career-changers entering data science and software engineering through lessons, workshops, and one-on-one sessions covering Python, Machine Learning, and SQL.
Comfortable teaching across the full stack — software design & development, machine learning, data science, and data engineering — for both university students and industry career-changers.
III IT Consulting
Independent consulting for businesses that need a technical hand — from a tired website to a fully automated workflow with AI baked in.
Website Design & Redesign
Modernising outdated or slow websites into fast, clean, maintainable builds.
Process & Task Automation
Identifying repetitive manual work and replacing it with reliable automated pipelines.
AI Tool Implementation
Scoping and integrating LLMs and ML tooling into real business workflows — not just demos.
Data & Analytics Advisory
Turning scattered data into dashboards, pipelines, and decisions leadership can trust.
IV Music
Off the clock, on the drum throne. Runs WerSalka — a recording & production studio — and fronts Chica Moustache on vocals and rhythm guitar.
WerSalka Studio
Recording, mixing, and production for bands and solo artists. Drum recording, full-band tracking, and production from raw takes to finished single.
The Fancy Note
Recorded drums for the band's singles.
Haust
Recorded all drums on the album.
Igray
Live sessions, single recording and production.
Chica Moustache
Recorded all the instruments for the project.
Also the vocalist & rhythm guitarist leading Chica Moustache —
Chica Moustache on Linktree ↗✦ Contact
Data project, guest lecture, consulting gig, or a track that needs drums — reach out.