We build open source so developers can use, inspect, and improve the tools they rely on. We maintain these projects with the community, learning from how people use them in production.
Here you'll find libraries for app development, testing, and performance, alongside developer tools and infrastructure for AI agents. Our roots are in React and React Native, but our agent tooling also supports work beyond those frameworks. Check each repository's documentation for supported platforms and requirements.
We are React Native Core Contributors and Founding Members of the React Foundation.
Browse our open-source projects and Callstack Incubator.
Found a bug or a gap in the docs? We'd welcome your help. Bug reports with reproductions make problems easier to investigate, and documentation improvements help other developers use the tools.
For code changes, start with the repository's contribution guide.
