Konstantin Käfer
Principal Software Engineer at Mapbox
Berlin, Germany
Summary
🤩
Rockstar🎓
Top SchoolKonstantin Käfer is a Principal Software Engineer based in Berlin with 18 years of experience building high-performance mapping and graphics systems, spanning C++, OpenGL/WebGL, Node.js and JavaScript. He has grown through multiple technical and leadership roles at Mapbox, shaping core rendering, styling and tooling for vector tiles and map design (including contributions to mapbox-gl-js, Mapnik and TileMill). Konstantin blends deep back-end systems work—like optimizing Mapnik’s rendering pipeline and node-mapnik bindings—with front-end refinements such as improved draw interactions and text/icon rendering for WebGL maps. He’s a pragmatic engineer who also improves developer ergonomics, e.g., enhancing clang-format integration for Xcode and hardening test suites and SQLite bindings. Experienced in template-based C++ refactors and performance-sensitive geometry algorithms (earcut.hpp), he brings both algorithmic rigor and product-focused polish. Colleagues rely on him to turn nuanced map-rendering problems into robust, maintainable solutions.
18 years of coding experience
15 years of employment as a software developer
Master of Science IT Systems Engineering, Master of Science IT Systems Engineering at Hasso Plattner InstituteAbitur Physics French, Abitur Physics French at Georg-Wilhelm-Steller-GymnasiumMaster of Science Computer Science, Master of Science Computer Science at University of Jyväskylä
German, French, English
Github Skills (58)
algorithm10
webgl10
assertion10
polygons10
objective-c10
map-box10
javascript10
c-language10
sqlite10
mapbox-gl-js10
compilation10
mapbox-gl10
rendering10
testing10
css10
Programming languages (18)
Github contributions (5)
mapbox/XcodeClangFormat
Sep 2016 - Jul 2020
Format code in Xcode 8+ with clang-format
Role in this project:
Software Engineer
Software EngineerContributions:3 releases, 29 commits, 17 PRs in 3 years 10 months
Contributions summary:Konstantin primarily contributed to the XcodeClangFormat project by improving the core functionality and user experience. They implemented the ability to format code using individual lines instead of replacing the entire buffer, preserving selections and breakpoints. Furthermore, they added a feature to format an entire file. The user also addressed a compile issue, implemented Objective-C language detection and fixed character encoding handling. The user made several commits aimed at ensuring compatibility and improving functionality.
clangclang-formatcode-formatxcodexcode-plugin
TryGhost/node-sqlite3
Feb 2011 - Feb 2016
SQLite3 bindings for Node.js
Role in this project:Back-end Developer
Back-end DeveloperContributions:230 commits, 1 PR, 1 push in 5 years
Contributions summary:Konstantin made several contributions related to SQLite3 bindings for Node.js. Their work included implementing support for blob data, which required modifying the `statement.cc` file to handle binding and unbinding blob objects. They addressed error handling in `.step()` functions by acquiring proper error messages. Moreover, they also made adjustments to test files by updating tests to work with the latest version and fixing memory management issues.
node-jsjavascriptsqlite3sqlitenodejs
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