esbuild and Rollup represent two different philosophies in JavaScript build tools. esbuild, written in Go, prioritizes extreme compilation speed—achieving 10-100x faster builds than traditional JavaScript-based bundlers. Rollup, written in JavaScript, focuses on producing highly optimized bundles with superior tree-shaking, making it the de facto standard for library authors publishing to npm.
This comparison matters because choosing the wrong tool impacts your entire development workflow. esbuild excels in speed-critical scenarios like CI/CD pipelines and rapid development iteration, while Rollup dominates the library ecosystem with its ability to generate multiple output formats and produce minimal bundle sizes. Application developers seeking fast builds and library maintainers optimizing package size represent the primary audiences for each tool respectively.
Choose esbuild when build speed directly impacts your workflow—CI/CD pipelines, large monorepos, or applications where rapid iteration matters more than squeezing every byte from the bundle. Its 10-100x speed advantage translates to real productivity gains during development, and it works excellently as a bundling step within frameworks like Vite (which uses esbuild for development and Rollup for production). For internal applications where you control the deployment environment and a few extra kilobytes don't matter, esbuild's speed wins.
Choose Rollup when you're building libraries for npm, UI component packages, or any code that others will consume as dependencies. Its superior tree-shaking, multiple output format support (CJS/ESM/UMD), and careful handling of external dependencies make it the industry standard for library publishing. The slower build times are acceptable because library builds happen less frequently than application development cycles, and the bundle size savings directly benefit every downstream user. For production application builds where bundle size impacts user experience (e.g., client-side JavaScript), Rollup's optimization advantage justifies the build time cost.