Jakob Keller
Chief Technology Officer at Ponte Energy Partners
Dusseldorf, North Rhine-Westphalia, Germany
Summary
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Rockstar🎓
Top SchoolJakob Keller is a technology executive and CTO based in Düsseldorf with six years of focused experience leading engineering and operations in the energy and storage sector. He blends strategic leadership at Ponte Energy Partners with hands-on performance engineering, contributing optimizations to the widely used Polars dataframe library to improve Python API speed and stability. His background spans operations, trading, and consulting roles, giving him a strong mix of technical, commercial, and process-oriented expertise. Educated at Technical University of Munich with additional studies at UC Berkeley, CDTM and NUS, he brings both business acumen and technology management training. Jakob is comfortable moving between high-level strategy and low-level code performance work—a combination that helps translate product requirements into scalable, efficient implementations. Colleagues would note his uncommon pairing of CTO responsibilities with direct contributions to open-source performance hotspots.
6 years of coding experience
Innovation Management, Innovation Management at University of California, BerkeleyBusiness, Business at National University of SingaporeDiplom Business Administration Computer Science, Diplom Business Administration Computer Science at Technical University of MunichHonours Degree Technology Management, Honours Degree Technology Management at Center for Digital Technology and Management (CDTM)
English, German, French, Spanish
Stackoverflow
43reputation
3kreached
0answers
1question
Github Skills (20)
performance-analytics10
performance-monitor10
python10
dataframes10
polar10
performance-measurement10
dataframe10
performance-analysis10
polars10
performance-tuning10
performance-monitoring10
data-structure9
rust9
data-structures9
type-checking8
Programming languages (7)
Github contributions (5)
pola-rs/polars
Aug 2022 - Mar 2025
Dataframes powered by a multithreaded, vectorized query engine, written in Rust
Role in this project:
Back-end Developer / Performance Engineer
Back-end Developer / Performance EngineerContributions:14 reviews, 19 PRs, 74 comments in 2 years 7 months
Contributions summary:Jakob primarily focused on performance optimizations within the Python codebase of the Polars dataframe library. Their contributions include improving the efficiency of critical functions like `expr_to_lit_or_expr`, `LazyFrame.with_columns()`, and `selection_to_pyexpr_list`. Additionally, they addressed type hinting and function naming issues, optimized schema handling and construction, and accepted more types in `from_records`, improving the usability of the library. The user's work directly enhanced the performance and stability of the Python Polars API.
polarsdataframespythondataframerust
jakob-keller/aiobotocore
Sep 2023 - Mar 2025
asyncio support for botocore library using aiohttp
Contributions:383 pushes, 200 branches in 1 year 6 months
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