rollup-plugin-license

3.7.1 verified Mon Apr 27 auth: no javascript

Rollup plugin that adds a license banner to the final bundle and generates a file listing all third-party licenses. Current stable version is 3.7.1, released with support for Rollup 4.x peer dependency. Key differentiators: supports multiple banner comment styles (regular, ignored, slash, none), file or string content with Lodash template interpolation, third-party license output with version deduplication, and custom data injection. Widely used for compliance in open-source and enterprise bundles. Ships TypeScript definitions. Maintained actively with regular updates.

Common errors

error Error: Cannot find module 'rollup-plugin-license' ↓

cause Package not installed or ESM-only module imported via require() in CommonJS context.

fix

npm install rollup-plugin-license --save-dev; in .cjs, use dynamic import: const license = await import('rollup-plugin-license').then(m => m.default)

error TypeError: license is not a function ↓

cause Importing the module incorrectly; likely using `require('rollup-plugin-license')` in ESM context.

fix

Use default import: import license from 'rollup-plugin-license'

error Error: Banner file not found: 'LICENSE' ↓

cause The path provided in `banner.content.file` is relative and may not resolve correctly.

fix

Use absolute path: path.resolve(__dirname, 'LICENSE')

error Error: Template execution failed: ... ↓

cause The banner contains invalid Lodash template syntax (e.g., unescaped `<%`).

fix

Escape template tags: use <%% for literal <% or remove template syntax.

Warnings

breaking Version 3.x dropped support for Node <14 and Rollup <1.x. The plugin now requires Rollup ^1.0.0 || ^2.0.0 || ^3.0.0 || ^4.0.0. ↓

fix Upgrade Node to >=14 and Rollup to ^1.0.0 or higher.

deprecated The option `dependencies` in banner template data is deprecated since version 3.0.0. Use `thirdParty` options instead. ↓

fix Use `thirdParty.dependencies` or `thirdParty.output`.

gotcha Using `commentStyle: 'ignored'` may not work in some minifiers (e.g., Terser) if they strip all comments by default. Ensure your minifier is configured to keep the banner. ↓

fix Set minifier option to preserve comments, e.g., terser({ format: { comments: 'all' } }).

gotcha The banner content is processed as a Lodash template with `dependencies` array. If the template contains `<%` or `%>`, these must be escaped or the plugin will throw a lodash error. ↓

fix Use `data` function to pass custom escaping or avoid template tags in banner.

breaking Version 0.10.0 changed `banner` from string to object with `content` and `commentStyle`. String usage still works but with deprecation warning. ↓

fix If passing a string, use `banner: 'your string'` or `banner: { content: 'your string' }`.

Install

npm install rollup-plugin-license

yarn add rollup-plugin-license

pnpm add rollup-plugin-license

Imports

license (default)
wrong
```
const license = require('rollup-plugin-license')
```
correct
```
import license from 'rollup-plugin-license'
```
This package is ESM-only; CommonJS require() will work in Node >=14 but the default export is a function. Use dynamic import() or ESM syntax in Rollup config.
license (type import)
```
import type { LicenseOptions } from 'rollup-plugin-license'
```
TypeScript types are bundled; use import type for options interface.

license (in CommonJS via .cjs)

wrong

const license = require('rollup-plugin-license')

correct

const license = await import('rollup-plugin-license').then(m => m.default)

For .cjs config files, use dynamic import() to access the default export.

Quickstart

Shows a minimal setup with banner from file and third-party license output.

// rollup.config.js (ESM)
import license from 'rollup-plugin-license'
import path from 'node:path'

export default {
  input: 'src/main.js',
  output: { file: 'dist/bundle.js', format: 'esm' },
  plugins: [
    license({
      sourcemap: true,
      banner: {
        content: {
          file: path.resolve('LICENSE'),
          encoding: 'utf-8',
        },
      },
      thirdParty: {
        includePrivate: false,
        includeSelf: true,
        output: {
          file: path.resolve('dist/dependencies.txt'),
        },
      },
    }),
  ],
}