John Källén
Software Engineer
Greater Stockholm Metropolitan Area Sweden
Summary
🤩
RockstarJohn Källén is a seasoned software engineer with 18 years' experience based in the Greater Stockholm area, known for a curiosity-driven approach to dissecting and rebuilding complex systems. He contributes to and maintains the Reko binary decompiler, where his backend work added support for architecture-specific instructions, improved stack variable handling, and enhanced format-string processing—demonstrating deep expertise in low-level tooling and reverse engineering. Comfortable in large, refactored codebases, he focuses on practical improvements that increase correctness and extensibility. Colleagues would describe him as methodical and hands-on, preferring to learn by taking software apart and putting it back together to reveal better designs.
18 years of coding experience
English, Swedish, Spanish, French, German
Stackoverflow
7,747reputation
1.1mreached
119answers
58questions
math
top-5%
visual-studio
top-5%
Github Skills (15)
static-code-analysis10
code-analysis10
csharp10
reverse-engineering10
dotnet-core10
visual-studio9
math9
low-level6
vector6
modulo6
brightscript6
bit6
roku6
pointer6
integer-division6
Programming languages (9)
Github contributions (5)
uxmal/reko
Sep 2007 - Jan 2023
Reko is a binary decompiler.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:26 releases, 137 reviews, 8208 commits in 15 years 7 months
Contributions summary:John was actively involved in the development and maintenance of the Reko decompiler, a binary decompiler. Their contributions focused on enhancing the software's core functionality, including adding the support for features like handling printf format string specifiers and the introduction of support for various assembly instructions and architecture-specific instructions. They also refactored the codebase, optimizing the handling of stack variables, and implementing functionality to add support for features related to different processors and image formats.
disassemblerisc-vdotnetcapstonedecompile
uxmal/reko-avalonia
Nov 2021 - Mar 2022
Contributions:8 commits, 4 pushes, 1 branch in 4 months
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