SWC (Speedy Web Compiler) is an extensible Rust-based platform for compiling and transforming JavaScript and TypeScript code into widely compatible JavaScript. It is designed as a high-performance alternative to tools like Babel and TypeScript’s compiler, focusing heavily on speed and scalability for modern web development workflows.

SWC takes modern JavaScript or TypeScript—often using advanced language features—and compiles it into backward-compatible JavaScript that can run in older browsers or environments. It supports parsing, transformation, and minification, and can be integrated into build systems, bundlers, and frameworks.

A key design goal of SWC is performance. By being written in Rust and using parallelization where possible, it achieves significantly faster build times compared to traditional JavaScript-based compilers. It is widely adopted in modern tooling ecosystems and is used in projects such as Next.js, Parcel, and Deno, as well as by large engineering organizations.

SWC is also designed to be modular and extensible, with support for custom transforms, plugins, and integration into developer toolchains. It can be used both as a standalone CLI tool and as a library or Node.js binding, making it flexible for different build architectures.

Key features include:

• High-speed JavaScript and TypeScript compilation written in Rust
• Transpilation of modern JS features to older environments
• Built-in minification and optimization support
• Integration with bundlers, frameworks, and test tools (e.g., Jest, Webpack loaders)
• Extensible architecture with support for custom transforms and plugins

Common use cases include:

• Compiling TypeScript in large-scale applications
• Speeding up frontend build pipelines
• Replacing Babel in modern toolchains
• Minifying production JavaScript
• Powering framework-level build systems like Next.js

SWC is an open-source project created by Korean developer kdy1 and maintained by a community of contributors.