tsup is a zero-config TypeScript bundler powered by esbuild. It prioritizes speed and simplicity, making it ideal for quickly building modern JavaScript libraries. With automatic externalization of dependencies and support for various output formats (ESM, CJS, IIFE), tsup streamlines the bundling process. Its minimal configuration reduces boilerplate, letting developers focus on writing code instead of build scripts. Popular for its efficient build times and ease of use, tsup is a valuable tool for any TypeScript project.