Szymon Chmal

Szymon Chmal

Software Developer

Passionate React developer with experience in Next.js, Astro, Angular, and Node.js, always eager to explore new technologies. Public speaker with 24+ talks on web performance and accessibility, making complex topics engaging. Founder of Google Developer Groups Toruń, dedicated to knowledge sharing, mentoring, and improving the web.

What I’ve been shipping

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Why Knowing Your App’s Bundle Contents Matters for React Native Performance

Learn why your React Native app’s bundle size matters & how tools like Expo Atlas help you optimize performance, reduce app startup time & improve dependency management.

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What's New in Next.js 15

Tune in to our breakdown of everything new in Next.js 15, from React 19 and React Compiler support to Turbopack and secure Server Actions.

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Master JavaScript Performance in React Native (Part 2)

Learn to fix JS performance issues in React Native—from debounce bugs to Redux selectors—in this hands-on webinar with real code examples.

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I Built a File-Based Router for React Native

A deep dive into building a file-based router for React Native using Metro’s hidden APIs—dynamic routing, loading states, and smart hacks included.

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Master JavaScript Performance in React Native (Part 1)

Watch Callstack's webinar on React Native JS performance. Learn to fix bottlenecks, leaks & FPS issues from the 2025 Ultimate Guide authors.

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State of React 2024 Breakdown

Let's take a deep dive into the long-awaited State of React survey from 2024; brace yourselves for a two-hour ride.

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LynxJS: First Impressions, Live Coding & What’s Under the Hood

We’re checking out LynxJS for the first time! Join us as we test it out, see how it works, and share their thoughts.

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Create React App is Out: Exploring Alternatives & Community Proposals

CRA is now deprecated, so we explore other options for starting web React projects, going through Vite, TanStack Router, Parcel, and Rsbuild to check the developer experience.

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Astro – Island Technology in the Name of Optimization

Next.js is the default choice, but Astro offers strong competition in some areas. Let's compare their features and differences.

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