Szymon Chmal

Expert Software Engineer at Callstack, building the React Native tools I wish I had.

I spend most of my time deep in developer tooling: debugging infrastructure, custom runtimes, testing systems, and the kind of React Native internals work that usually starts with reverse-engineering something undocumented. I build in the open, speak at conferences, and care a lot about making the developer experience feel sharper, faster, and a little less painful.

What I'm building

Rozenite - A React Native DevTools plugin framework that also brings the experience to the web and to agents.
Voltra - Build Live Activities and widgets for iOS and Android with server-side rendering, updates, and React Native-first ergonomics.
Harness - My go-to tool for testing native modules without mocks, but with the developer experience of writing tests in Jest.
React Native Grab - Select a UI element and copy its context to an agent, enabling surgical changes without wasting tokens on exploration.

Speaking

I speak regularly about React Native internals, DevTools, testing, rendering, and the weird engineering rabbit holes that somehow turn into useful tools.

I've given 50+ talks across conferences, meetups, and community events. More of that lives on chmal.it/talks.

GitHub Sponsors

If my work has saved you debugging time, helped your team ship faster, or made React Native feel more manageable, sponsoring me is a practical way to say thanks. It directly funds the evenings and weekends I spend pushing ideas further, polishing rough edges, and building more of the tooling I want this ecosystem to have.