Jan Wassenberg
Senior Staff Software Engineer at Google DeepMind
Zurich, Zurich, Switzerland
Summary
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Rockstar🎓
Top SchoolJan Wassenberg is a Senior Staff Software Engineer in Zurich with over a decade of experience building high-performance systems across CPU architectures from AVX-512 to SVE2, NEON and RISC-V. At Google DeepMind he leads Gemma.cpp inference R&D and founded the Highway SIMD library, bridging research-grade performance engineering with production-ready open source. His background includes optimizing image codecs (editor of the JPEG XL standard) and shipping core multimedia infrastructure at Blackmagic’s DaVinci Resolve, demonstrating deep expertise in SIMD, build systems and cross-platform performance. Contributions to projects like libjxl, highwayhash and gemma.cpp show a consistent focus on portability, low-level optimization and rigorous build/test infrastructure. He combines research credentials (Dr.-Ing. in Informatics from KIT) with hands-on systems architecture, making him equally at home proving algorithmic speedups or fixing tricky cross-platform build issues. A less obvious strength is his track record of practical standards and tooling work that improves interoperability across languages and platforms.
10 years of coding experience
8 years of employment as a software developer
Dr.-Ing. Informatics, Dr.-Ing. Informatics at Karlsruhe Institute of Technology (KIT)
english (native), german (native), French
Stackoverflow
54reputation
4kreached
3answers
0questions
Github Skills (29)
c-language10
jpeg-xl10
lossless-compression10
matrix-multiplication10
build-system10
vectorization10
performance-optimization10
bazel10
hashing-algorithm10
cprogramming-language10
linear-algebra10
image-compression10
multiplatform9
cross-platform9
platform-independent9
Programming languages (18)
Github contributions (5)
google/gemma.cpp
Feb 2024 - Apr 2025
lightweight, standalone C++ inference engine for Google's Gemma models.
Role in this project:
Back-end Developer & Performance Engineer
Back-end Developer & Performance EngineerContributions:180 reviews, 3 PRs, 16 pushes in 1 year 1 month
Contributions summary:Jan primarily contributed to the C++ inference engine for Google's Gemma models. They focused on bug fixes, such as adding missing elements and resolving lambda-related issues within the `ops.h` file. Furthermore, the user worked on performance optimizations, including code-level adjustments and integration of optimized matrix multiplication routines.
google/highwayhash
Mar 2016 - Aug 2022
Fast strong hash functions: SipHash/HighwayHash
Role in this project:Back-end Developer
Back-end DeveloperContributions:10 reviews, 124 commits, 40 PRs in 6 years 6 months
Contributions summary:Jan's contributions primarily involve fixing build processes and improving the codebase's interoperability within the `google/highwayhash` repository, which focuses on fast and strong hash functions. They removed a reference and added a workspace for Bazel builds. The user modified the header files to use `extern "C"` for language interop and revised the internal state size. They added several new versions of the HighwayTreeHash function and further improved it for better performance.
hashhighwayhashhash-functionssiphashhash-algorithm
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