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bundlejs - Online bundler + npm package bundle size checker


a quick npm package size checker

Changelog (July 8, 2023): The subtle shift in bundlejs' behaviour with ESM & CJS
✨ WOOOH! ✨ The official bundlejs API is out, you can access it via and/or The new API also comes with proper badges spring-easing'a badge


No logs...



Enable the analysis config to view the size of output files with interactive zoomable charts.

  "analysis": "treemap" | "network" | "sunburst" | true | false,
  "esbuild": { ... }

Nothing to analyze...

📑 Official Docs for bundlejs are now available.
Special thanks to @upstash for sponsoring the bundlejs API.


When bundling packages that also export CSS and other external files, now checks the gzip/brotli size of these external files, even though it won't output any code. Keep this in mind this isn't a bug, however, if it causes confusion I am willing to change this behaviour.

Treeshaking is available, but not all CDNs support access to each packages package.json so there might be slight package version conflicts. The only verified CDN with access to the package.json is

Check the console for error messages and warnings.

You can use custom protocols to specify which CDN the module should come from.


import { toStr } from "skypack:@okikio/animate";
// or
export * from "esm:@okikio/animate"; 
// or 
export { animate } from "";

* If an error occurs try using a different CDN, by default bundle uses but you can use the others.

* For some packages an error occurs where the default export is excluded from the treeshaken bundle, the solution for this is to manually include the default export like so,

export * from "solid-dismiss";
// and
export { default } from "solid-dismiss";


Externals allow you to mark certain modules as modules to exclude from resolving, loading, and bundling, you use it the way you'd use the esbuild externals config option, e.g.

  "esbuild": {
    "external": ["react", "react-dom"],

You can try it out below,{"esbuild":{"external":["@okikio/animate"]}}.

Check out a complex example of using the external config{"esbuild":{"external":[...]}}


Aliases act as a redirect for modules, they are for replacing packages with different ones, e.g. replace fs with memfs, so, it can work on the web, etc..

You use aliases like this

  "alias": {
    "@okikio/animate": "react-dom"

You can try out an example of using aliases,{"alias":{"@okikio/animate":"react-dom"}}.

⚠️ Warning: aliases currently don't care about the original packages version, e.g. @okikio/animate@beta will be redirected to react-dom regardless of the package version in use.


You can also add bundle badges, they look like this,

All you need to do is to add this to your
# Light Mode Badge 
[![Open Bundle](](

# Dark Mode Badge 
[![Open Bundle](](

Another options is to use the API, e.g.

spring-easing's badge

[![spring-easing's badge](](

You can use the Sharing section above and the 📑 Official Docs to learn how to create unique bundles via badges.

Community, Backers & Sponsors

Tweet at me on @jsbundle with what you love and what you think needs improvement in bundlejs.
Note You can also use to access bundlejs.