Szymon Kapala / Turbo_Szymon

Building native-feeling software at the edge of React Native.

CTO at Margelo, react-native-nitro-fetch co-author, and co-author of React Native libraries for crypto, networking, profiling, runtimes, and app performance. React Native Reanimated 2.0 co-author and former Expo team member.

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Profile

A product-minded engineer with systems taste.

I work where application polish meets native runtime detail: animation systems, mobile infrastructure, project delivery, team leadership, and the APIs developers depend on every day.

Skills

Performance, native internals, and production delivery.

Mobile app performance improvements · 7 years · 50+ apps improved20+ performance tools, mostly customAI integrations, especially on-deviceLocal-first appsNative modulesNative componentsFabric inside-outReact Native core inside-outHermes inside-outCI tests0 to 1 product engineeringPlanning architectureResearching modern technical approachesLeading projectsManaging teams of developersC++KotlinObjective-CTypeScriptSwiftJavaRust

Open source

Libraries I co-authored and framework work in flight.

Co-author

react-native-nitro-fetch

A Nitro-powered networking stack for React Native focused on startup speed, request prefetching, and reducing the cost of data loading on real production apps.

Co-author

React Native Reanimated 2.0

Co-created the 2.0 generation: worklets, the first Babel plugin, and layout animations. Newer Reanimated versions continued beyond my direct work.

Co-author

react-native-bignumber

Native big-number arithmetic for React Native, aimed at finance, crypto, and other precision-heavy apps where JavaScript number semantics are not enough.

Co-author

react-native-quick-crypto

A C++/JSI implementation of Node-compatible crypto APIs, built so wallets, encrypted apps, and security-sensitive React Native code can avoid slow JS polyfills.

Co-author

react-native-release-profiler

Release-build profiling for Hermes apps: capture where JavaScript time goes in the conditions users actually run, instead of relying on misleading debug-mode traces.

Co-author

react-native-runtimes

Tools for creating and controlling additional JavaScript runtimes in React Native, useful for isolating heavy work, experiments, and off-main-thread execution patterns.

In review

React Native contributions I hope to land.

React Native PR #56078

UIManager constants cache

Proposal to cache UIManager constants in bridgeless new architecture on Android, aiming to improve startup on low and mid-range Android devices by 150-300ms.

Hermes PR #2029

JSON tree materialization

Proposal for a JSI JSON tree materialization path so native data can become Hermes values without round-tripping through JSON text on the JS thread.

Experience

From app teams to framework infrastructure.

Jan 2022 – Present · 4 yrs 7 mos

CTO at Margelo

Managing projects and developers, estimating technical scope, unblocking engineers when they get stuck, and staying close to architecture and React Native performance work. I also build performance tooling and native infrastructure used to improve production mobile apps.

Oct 2021 – Feb 2022 · 5 mos

React Native Developer at Lowkey

Contract React Native development focused on production app work and native-feeling mobile experiences.

Jul 2018 – Oct 2021 · 3 yrs 4 mos

Software Engineer at Software Mansion

Worked through Software Mansion on React Native infrastructure, including Expo team work and React Native Reanimated 2.0. My Reanimated work covered worklets, the first Babel plugin, and layout animations.

Contact

Let’s talk about React Native.

github.com/Szymon20000x.com/Turbo_SzymonLinkedInmargelo.com
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