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4.2.5 • Public • Published

BundleStats screenshot

Demo: Compare multiple builds, Single build

BundleStats webpack plugin

Analyze webpack stats(bundle size, assets, modules, packages) and compare the results between different builds.

Node version GitHub action CodeQL


- Bundle size and totals by file type(css, js, img, etc)
- Cache invalidation, Initial JS/CSS and other bundle specific metrics
- Assets report (entrypoint, initial, types, changed, delta)
- Modules report (changed, delta, chunks, duplicate count and percentage)
- Packages report (count, duplicate, changed, delta)
Side by side comparison for multiple builds

Table of Contents


npm install --dev bundle-stats-webpack-plugin


yarn add --dev bundle-stats-webpack-plugin

Webpack configuration

// webpack.config.js
const { BundleStatsWebpackPlugin } = require('bundle-stats-webpack-plugin');

module.exports = {
  plugins: [
    new BundleStatsWebpackPlugin()


  • compare - use local saved stats for comparison (default true).
  • baseline - save current webpack stats as baseline (default false).
  • html - output html report (default true).
  • json - output json report (default false).
  • outDir - output directory relative to webpack output.path (default '').
  • silent - stop logging info and only log warning and error (default false).
  • stats - Webpack stats options default:
      stats: {
        assets: true,
        chunks: true,
        modules: true,
        builtAt: true,
        hash: true

Use with create-react-app

You will need to customize the default webpack config. That can be done by using react-app-rewired which is one of create-react-app's custom config solutions. You will also need customize-cra.

npm install --dev customize-cra react-app-rewired


yarn add customize-cra react-app-rewired --dev

Change your default scripts in package.json to:

/* package.json */
"scripts": {
  "start": "react-app-rewired start",
  "build": "react-app-rewired build",
  "test": "react-app-rewired test"

Create a file config-overrides.js at the same level as package.json.

// config-overrides.js
const { override, addWebpackPlugin } = require('customize-cra');
const { BundleStatsWebpackPlugin } = require('bundle-stats-webpack-plugin');

module.exports = override(
  addWebpackPlugin(new BundleStatsWebpackPlugin()),

Compare mode

In compare mode, the metrics are compared against an existing(node_modules/.cache/bundle-stats/baseline.json) Webpack stats file(baseline). To generate the baseline webpack stats, set BUNDLE_STATS_BASELINE environmental variable to true or set BundleStatsWebpackPlugin baseline option to true:

# Checkout to the branch/tag/commit where you want to generate the baseline
$ git checkout master

# Build your application with BUNDLE_STATS_BASELINE environmental variable
$ BUNDLE_STATS_BASELINE=true npm run build

# Checkout to the working branch/tag/commit
$ git checkout MY_FEATURE_BRANCH

# Build your application
$ npm run build

The option can be disabled by setting BundleStatsWebpackPlugin compare option to false.

Other packages


npm npm

CLI to generate bundle stats report.


npm npm

Gatsby plugin for bundle-stats.


npm npm

Next.js plugin for bundle-stats.

Related projects

🌀 relative-ci.com

In-depth webpack bundle analysis and monitoring

RelativeCI automates webpack bundle analysis, monitoring, and alerting so you can identify and fix bundle regressions before shipping to production:

  • 🔮 Analyze webpack bundle stats on every build
  • 📈 Monitor webpack bundle stats changes and identify tendencies over extended periods
  • 🔔 Get notified via GitHub Checks, GitHub Pull Request comments, and Slack notifications
  • 🔨 Support for all major CI services (CircleCI, GitHub Actions, Gitlab CI, Jenkins, Travis CI)
  • 💕 Always free for Open Source

Try for free

🌓 relative-ci/compare

Standalone web application to compare Webpack/Lighthouse/Browsertime stats.

Compare bundle stats


Github Action that generates bundle-stats reports.


npm i bundle-stats-webpack-plugin

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  • vio
  • bundle-stats-bot