Jan Kalfus
Senior Software Developer at Kontent.ai
Brno, Southeast, Czechia
Summary
👤
Senior🎓
Top SchoolJan Kalfus is a Senior Software Developer based in Brno with 10 years of experience building and leading full‑stack projects using TypeScript/React and C#/.NET, with strong expertise in frontend performance and user-focused UX. At Kontent.ai he leads feature delivery, drove a move to a monorepo, introduced Sentry monitoring, and runs workshops to elevate team skills—combining hands‑on coding with project leadership. He has a history of shipping successful SPA redesigns and simplifying E2E testing, and contributes to open source React Native UI components where he fixed cross‑platform UI/UX issues like Android FAB shadow rendering. Comfortable across cloud tooling (Azure, KQL) and mobile, he pairs pragmatic engineering discipline with continuous learning and an eye for polished interfaces.
9 years of coding experience
7 years of employment as a software developer
Magister (Mgr.), Service Science, Management and Engineering, Magister (Mgr.), Service Science, Management and Engineering at Masarykova univerzita BrnoBachelor (Bc.), Information Technology, Bachelor (Bc.), Information Technology at Vysoké učení technické v Brně, Fakulta informačních technologiíComputer Science, Computer Science at Technological Educational Institute of Crete
English, German
Stackoverflow
5,672reputation
606kreached
37answers
19questions
code-first
top-5%
jwt
top-5%
entity-framework
top-5%
webrtc
top-5%
react-redux
top-5%
javascript
top-5%
Github Skills (27)
react-native10
mobile-development10
component-development10
android-development10
asp-net-core-web-api10
android10
native-android10
react-redux9
javascript9
ux-design9
datetime9
ui-design9
webrtc9
jwt9
code-first9
Programming languages (11)
Github contributions (5)
mastermoo/react-native-action-button
Aug 2016 - Aug 2016
customizable multi-action-button component for react-native
Role in this project:
Mobile Developer (Android/iOS)
Mobile Developer (Android/iOS)Contributions:5 commits, 3 PRs, 4 comments in 2 days
Contributions summary:Jan primarily focused on fixing UI/UX issues within the react-native-action-button component. Their commits addressed visual discrepancies, specifically button shadow rendering on Android devices. The changes included modifications to `ActionButton.js` and `ActionButtonItem.js` files, adjusting shadow properties and fixing the cropped FAB issue. The user also merged a branch, indicating involvement in code integration.
reactreact-nativeandroidbuttoncustomizable
jankalfus/DefinitelyTyped
Aug 2016 - Jan 2020
The repository for high quality TypeScript type definitions.
Contributions:7 pushes, 1 branch in 3 years 5 months
compilationtype-definitionshigh-qualitydefinitionstypescript
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