Karol Janyst
Sr. Software Engineer II at AXS
Chiyoda, Japan
Summary
👤
Senior🎓
Top SchoolKarol Janyst is a senior full-stack engineer with 15 years of experience building high-traffic, customer-facing web platforms across Japan, Europe and the US. He combines strong front-end expertise in React and modern micro-frontend architectures with backend work in JVM languages, Scala, Python and TypeScript, and has driven performance and developer-experience improvements at scale. At AXS he mentors engineers and leads initiatives to boost system performance and revenue; at PayPay he migrated CI/CD to cost-efficient AWS-hosted runners and implemented DevSecOps protections for PII. A Warsaw University of Technology master's graduate, he pairs practical production experience with academic rigour and cross-cultural collaboration based in Tokyo. An active open-source contributor, he has improved internationalization for the popular validatorjs library by adding Polish and Japanese locales and enhancing date validation rules—demonstrating attention to global user experience.
15 years of coding experience
13 years of employment as a software developer
Master's degree, Computer Engineering, Master's degree, Computer Engineering at Warsaw University of Technology
English, Polish, Japanese
Github Skills (11)
j10
javascript10
lang10
localization10
japa10
validation10
validations10
nodejs8
laravel7
laravel-mix7
browser7
Programming languages (14)
Github contributions (5)
mikeerickson/validatorjs
Jun 2016 - Jul 2016
A data validation library in JavaScript for the browser and Node.js, inspired by Laravel's Validator.
Role in this project:
Localization / Internationalization Specialist
Localization / Internationalization SpecialistContributions:15 commits, 3 PRs, 22 comments in 18 days
Contributions summary:Karol primarily focused on adding and updating language translations for the validatorjs library. Their commits included the creation of new language files (Polish and Japanese) and the correction of existing ones. This involved translating error messages and other text strings to provide internationalization support. Furthermore, they added a date rule to the validation to improve accuracy for users.
laravel-sbrowservalidationnode-jsjavascript
LKay/react-transition-replace
Aug 2017 - Jul 2018
A React component to animate replacing one element with another.
Contributions:14 releases, 52 commits, 22 PRs in 11 months
react-componentreactanimationanimateanimate-replacing
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