babel

Babel is a widely used open-source JavaScript compiler, described in its README as "the compiler for writing next generation JavaScript." It lets developers write code using the latest JavaScript features and compiles those features down to a version supported by their target environments when native support is missing. The README illustrates this with an example: ES2020 nullish coalescing (`input ?? "Hello world"`) is transformed into an equivalent expression using a conditional check (`input != null ? input : "Hello world"`). A linked REPL is provided for trying transformations interactively. The project is community-driven and maintained by a group of volunteers, with funding through Open Collective and GitHub sponsors. The README lists sponsors and backers, and invites contributions of developer time or funds. Support channels include GitHub Discussions, a Slack community, Stack Overflow, and Bluesky. Documentation lives on the project website, and bug reports or feature requests go through the repository's issue tracker following CONTRIBUTING.md. The repository is organized as a monorepo composed of many npm packages, with design notes on the monorepo structure. The README also points to contribution resources such as good first issue and help wanted labels, notes and roadmap repositories, tracking of TC39 proposals, a blog, videos, and a podcast. The project is released under the MIT license.