Kleis Wolthuizen
Sneek, Frisia, Netherlands
Summary
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Rockstar🎓
Top SchoolKleis Wolthuizen is a software engineer from Sneek, Netherlands, with 11 years of experience building high-performance backend systems and tooling for image processing at scale. He runs wsrv.nl, a service that dynamically processes millions of images per hour, and contributes to core open-source projects like libvips, sharp, emscripten and OSS-Fuzz, where his work spans C/C++ bindings, build systems, and performance optimizations. His contributions show a strong focus on reliability and maintainability—fixing subtle bugs, improving build and CI processes, and enabling multithreading and platform compatibility across Emscripten and Rust bindings. Comfortable across languages and layers, he blends systems-level engineering with practical DevOps and CI automation to keep complex image pipelines fast and robust.
10 years of coding experience
Bachelor's degree, Informatics, Bachelor's degree, Informatics at NHL Stenden Hogeschool
Stackoverflow
525reputation
729kreached
5answers
0questions
image
top-5%
Github Skills (61)
code-optimization10
performance-analytics10
mson10
jpeg-xl10
lib10
c-language10
performance-monitor10
code-profiling10
apidoc10
multithreading10
image-processing10
bash10
build-system10
cmake10
c1110
Programming languages (27)
Github contributions (5)
weserv/images
Dec 2015 - Nov 2022
Source code of wsrv.nl (formerly images.weserv.nl), to be used on your own server(s).
Role in this project:
Back-end Developer
Back-end DeveloperContributions:3 reviews, 465 commits, 19 PRs in 7 years
Contributions summary:Kleis's commits primarily focused on refactoring and improving existing functionality within the image processing service. They implemented changes related to image handling and manipulation libraries like Intervention Image and Guzzle, indicating a focus on backend tasks. The user also appears to be responsible for ensuring the code's compliance with PSR-2 standards.
nginximage-manipulationimage-serverbsd-3-clausedocker
libvips/libvips
Sep 2017 - Jan 2023
A fast image processing library with low memory needs.
Role in this project:Back-end Developer
Back-end DeveloperContributions:7 releases, 297 reviews, 280 commits in 5 years 5 months
Contributions summary:Kleis's primary focus was on enhancing the core functionality of the image processing library, libvips. They implemented improvements related to SVG and PDF input handling for thumbnail generation, which involved modifications to the relevant C code. Additionally, the user added and improved C++ bindings, by adding missing C++ functions, implementing new std::string overloads for certain features and adding a feature for handling of metadata, such as the ability to remove image metadata.
memorybmpimage-serverimagemagickjpeg
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