Andrzej Rybczak
Lead Developer at Scrive
Gdańsk, Pomeranian Voivodeship, Poland
Summary
🤩
Rockstar🎓
Top SchoolAndrzej Rybczak is a Lead Developer based in Gdańsk with 17 years of experience building robust, developer-friendly backend systems, primarily in Haskell and PostgreSQL. He has driven critical performance and scalability work at Scrive—designing automatic DB migration frameworks, custom libpq bindings, and optimizations that yielded up to 10x speedups—while leading teams toward reliable production systems. A seasoned open-source contributor, Andrzej has contributed to high-profile projects such as the Glasgow Haskell Compiler and Cardano-SL, improving concurrency, package management, and transaction/memory handling in crypto and compiler codebases. His background in mathematics and computer security informs a pragmatic focus on safe concurrency, correctness, and practical cryptographic bindings, making him a go-to engineer for complex backend and security-sensitive problems.
17 years of coding experience
8 years of employment as a software developer
Matematyka, Matematyka at Uniwersytet WrocławskiMaster of Science (MSc), Computer Security, Excellent, Master of Science (MSc), Computer Security, Excellent at Politechnika Wrocławska
English, Polish
Stackoverflow
78reputation
2kreached
2answers
2questions
Github Skills (22)
c-language10
package-management10
cryptocurrency10
blockchain10
ghc10
cprogramming-language10
haskell10
build-system9
concurrency9
stm9
generics8
cryptography8
locking8
code-optimization8
testing8
Programming languages (10)
Github contributions (5)
ncmpcpp/ncmpcpp
Jul 2012 - Aug 2021
Featureful ncurses based MPD client inspired by ncmpc
Role in this project:
Back-end Developer
Back-end DeveloperContributions:33 reviews, 1009 commits, 86 PRs in 9 years 2 months
Contributions summary:Andrzej's contributions primarily focused on enhancing and extending the functionality of the ncmpcpp MPD client. They made significant changes to the actions module, ensuring actions are executed with proper checks. Their code changes also included optimizations to filtering, enhancements to key bindings, and adjustments to playlist and tag editor interactions. Furthermore, they addressed bugs related to song listing and error reporting to improve usability and address some issues.
mpd-clientmpdmixerncursesnim-language
input-output-hk/cardano-sl
Jun 2017 - Mar 2018
Cryptographic currency implementing Ouroboros PoS protocol
Role in this project:Back-end Developer
Back-end DeveloperContributions:49 commits, 21 PRs, 14 pushes in 9 months
Contributions summary:Andrzej primarily contributed to the core functionality of the Cardano-SL cryptocurrency project. Their work involved modifications to Haskell code related to the Cardano-SL cabal file, as well as implementing and improving the transaction processing and memory state management. They also focused on security by implementing mutexes, and fixed linter warnings and other bugs.
cardanocryptographyposadacryptographic
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