Szymon Rybczak
Co-Founder & CEO at TesterArmy (YC P26)
San Francisco, California, United States
Summary
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RockstarSzymon Rybczak is a founder and mobile-focused engineering leader with five years of hands-on experience building React Native apps and developer tooling from San Francisco. As Co-Founder & CEO of TesterArmy (YC P26), he is driving autonomous QA testing while previously advancing React Native at Callstack and contributing notable iOS/Android fixes to flagship projects like facebook/react-native and the community CLI. He combines product-minded leadership with deep platform experience—shipping iOS-specific CLI features, improving dev menus, CI scripts, and dependency management to smooth developer workflows. Known for tackling device-specific build challenges and improving error handling, he blends startup grit with open-source impact across widely used mobile tooling.
5 years of coding experience
5 years of employment as a software developer
Stackoverflow
51reputation
2kreached
4answers
0questions
Github Skills (19)
ios10
react-native10
mobile-development10
mobile10
cli10
objective-c9
android9
xcode9
swift9
cross-platform8
app-framework8
javascript8
cicd7
firebase6
arraylist6
Programming languages (13)
Github contributions (5)
react-native-community/cli
Nov 2022 - Jan 2023
The React Native Community CLI — Command line tools to help you build React Native apps
Role in this project:
Mobile Developer (iOS)
Mobile Developer (iOS)Contributions:303 reviews, 5 commits, 234 PRs in 1 month
Contributions summary:Szymon primarily contributed to the iOS platform-specific aspects of the React Native CLI. They implemented features such as running apps on all booted devices and simulators. Additionally, the user addressed bugs related to device selection and target specification for iOS builds. Furthermore, they made changes to the build process and error handling for iOS applications.
clicommand-line-toolreact-native-appreact-native-communityreact-native
react/react-native
Aug 2022 - Jul 2025
A framework for building native applications using React
Role in this project:Mobile Developer
Mobile DeveloperContributions:36 reviews, 50 PRs, 84 comments in 2 years 11 months
Contributions summary:Szymon primarily contributed to the React Native framework, focusing on improvements and fixes related to the Android and iOS platforms. Their work included adding a feature to invoke the dev menu on iOS, bumping versions of dependencies such as Flipper and NDK, and updating error messages. They also made changes to CI/CD scripts, and implemented a fix for a rn-tester issue, enhancing the development workflow.
reactandroidapp-frameworkiosmobile
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