Klemen Košir
Staff Software Engineer at LY Corporation
Fukuoka Prefecture, Japan
Summary
🤩
Rockstar🎓
Top SchoolKlemen Košir is a Staff Software Engineer based in Fukuoka, Japan, with 15 years of experience building and hardening back-end systems and developer tooling. He has progressed through senior engineering roles at LINE and LY Corporation, combining deep backend expertise with test automation and QA improvements that raise long-term code quality. An active open-source contributor, Klemen has contributed bug fixes, new features and testing migrations to high-profile projects like Armeria and CentralDogma, and improved UX and performance in Promgen by touching both front-end and back-end code. He is comfortable across the stack—refactoring tests to JUnit 5, fixing floating-point and serialization issues, and modernizing front-end libraries—which reflects a pragmatic, detail-oriented approach. Klemen holds a Master’s in Computer and Information Science from the University of Ljubljana and brings a habit of quietly improving developer experience and documentation alongside feature work.
15 years of coding experience
10 years of employment as a software developer
Master’s Degree, Computer and Information Science, Master’s Degree, Computer and Information Science at University of Ljubljana, Faculty of Computer and Information Science
Slovenian, English, German, Japanese
Github Skills (48)
git10
javascript10
text-editor10
ui-elements10
testing10
git-repository10
c1110
package-repository10
java10
c1710
neovim10
vim10
regular-expression10
javas10
junit10
Programming languages (25)
Github contributions (5)
line/centraldogma
Jan 2020 - May 2021
Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2
Role in this project:
Back-end Developer & QA Engineer / Test Automation Engineer
Back-end Developer & QA Engineer / Test Automation EngineerContributions:4 reviews, 8 commits, 9 PRs in 1 year 3 months
Contributions summary:Klemen primarily focused on enhancing the testing infrastructure and migrating existing tests to JUnit 5 within the CentralDogma repository. They implemented and refactored testing components, including CentralDogmaExtension and CentralDogmaRule, to support JUnit 5 and improve testability. Their contributions involved converting integration and unit tests, addressing specific challenges like handling test parameters and adapting to JUnit 5's features, demonstrating a strong emphasis on quality assurance. The user also worked on refactoring and re-writing tests.
vcsconfigurationconfiguration-serverversion-controlzookeeper
line/armeria
Feb 2020 - Jan 2022
Your go-to microservice framework for any situation, from the creator of Netty et al. You can build any type of microservice leveraging your favorite technologies, including gRPC, Thrift, Kotlin, Retrofit, Reactive Streams, Spring Boot and Dropwizard.
Role in this project:Back-end Developer
Back-end DeveloperContributions:26 reviews, 20 commits, 25 PRs in 1 year 11 months
Contributions summary:Klemen primarily contributed to bug fixes, code enhancements, and the implementation of new features within the Armeria framework. Their work included resolving UI issues, improving code clarity, and adding support for new serialization formats like TTEXT_NAMED_ENUM. Furthermore, they addressed issues related to floating-point calculations and fixed problems with the documentation. They also made changes to the documentation and tests.
rpcmicro-frameworkretrofitprotobuftype-of
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