UberESM — Deduplicated ESM Bundler

This service takes a list of npm packages, runs npm install for flat semver resolution, then bundles them with esbuild's splitting: true to produce per-package ESM entry files with automatically deduplicated shared chunks.

1. Build packages

2. Import map

No build yet. Click "Build" above.

3. Use in your code



  
4. Speed up loading with modulepreload

  

    The browser does not proactively fetch import map entries —
    it only fetches a module when an import statement runs.
    <link rel="modulepreload"> tells the browser to start
    fetching entry files and their chunk dependencies in parallel
    during HTML parsing, before any module script executes.
  

  


  
5. Live demo

  
After building, a new tab opens with the import map injected and a working demo.