Jan Klausa
Senior Software Engineer at Mercari, Inc.
Tokyo, Japan
Summary
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RockstarJan Klausa is a Senior Software Engineer based in Tokyo with 12 years of experience building high-quality mobile and full-stack products. He has deep iOS expertise—contributing to flagship open-source projects like WordPress-iOS and AztecEditor—and a track record of shipping complex features from Core Data improvements to rich editor refactors. Jan has led product initiatives at scale, launching new shipping experiences and a car-selling flow at Mercari and setting up CI, release automation, and foundations for app rewrites at fast-growing startups. He smoothly transitioned to modern full‑stack work, delivering React/TypeScript front ends and Go backend improvements while documenting the learning path for his team. Pragmatic about trade-offs, he champions infrastructure, performance, and developer experience improvements that reduce long‑term cost of ownership. Outside obvious achievements, he’s comfortable navigating both distributed open-source collaboration and tightly coupled product delivery in high-impact, user-facing domains.
12 years of coding experience
10 years of employment as a software developer
English, German, Polish
Stackoverflow
61reputation
2kreached
0answers
1question
Github Skills (14)
html10
editors10
xcode10
swift10
coredata10
ios10
html-editor10
editor10
cocoapods10
wordpress9
objective-c9
airplay6
avplayer6
ipad6
Programming languages (10)
Github contributions (5)
wordpress-mobile/WordPress-iOS
Oct 2017 - Aug 2019
WordPress for iOS - Official repository
Role in this project:
Mobile Developer (iOS)
Mobile Developer (iOS)Contributions:1280 commits, 211 PRs, 315 pushes in 1 year 11 months
Contributions summary:Jan made several code contributions to the WordPress for iOS project, primarily focused on implementing and improving features related to displaying and interacting with stats data. They introduced enhancements for Core Data entities, including modifications to the `StatsInsightsStore`, `StatsRecord`, and several data models, showcasing a focus on data persistence and retrieval. Furthermore, they updated tests to reflect these changes, indicating a commitment to code quality and maintainability. The changes included adjustments to Core Data models and data mapping.
cocoapodsobjective-cwordpressswiftios
wordpress-mobile/AztecEditor-iOS
Dec 2017 - Dec 2017
A reusable native iOS visual HTML text editor component.
Role in this project:Mobile Developer (iOS)
Mobile Developer (iOS)Contributions:15 commits, 5 PRs, 11 pushes in 15 days
Contributions summary:Jan primarily focused on refactoring and improving the Aztec editor component for iOS. Their contributions involved restructuring code related to image and video handling, converting formatters to inserters, and modifying the representation of HTML elements. The user also made changes to support Dynamic Type, ensuring the text editor adapts to user-defined font sizes. Furthermore, they added tests to verify the persistence of certain HTML elements like `<hr>`.
html-text-editorios-nativeiosios-libraryhtml-text
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