Rollup Config Validator

Rollup is a modern, high-performance module bundler for JavaScript, favored by library authors and framework developers for compiling codebase structures into clean, distribution-ready formats. Unlike larger application bundlers, Rollup targets the ES Module (ESM) specification, offering advanced tree-shaking capabilities that remove unused code (dead code elimination) to produce the smallest possible bundle sizes.

Because Rollup is highly flexible, its configuration files (typically rollup.config.js orrollup.config.mjs) often grow complex. They coordinate multiple input entries, format different output specifications (ESM, CommonJS, UMD, IIFE), declare external dependencies, and configure pipelines of plugins (such as Babel, TypeScript, and minifiers).

Typing errors in option keys, mismatched format declarations, or conflicting output directives will break your build pipeline, leading to CI/CD errors or broken releases. Our free Rollup Config Validatorprovides a fast, browser-safe playground to check configurations for schema validity before starting a build.

Our validator scans your Rollup settings against the official Rollup configuration specification, checking the following parameters:

• Input Definition (input): Rollup requires identifying entry files. Theinput directive must be either a string path (e.g. "src/index.js"), an array of paths, or an object mapping names to entry paths for multi-entry code-splitting.
• Output Blocks (output): Output parameters specify how bundles are emitted. The validator verifies key properties inside the output object, checking that:
  • Both file and dir are not defined together (use file for single bundles, and dir for chunked/multiple builds).
  • The format is a valid bundler format: amd, cjs, es,iife, system, or umd.
  • Scalar properties like sourcemap use valid types (booleans or strings "inline" /"hidden").
• Dependency Management (external): Helps prevent bundling peer dependencies by validating that the external list is a string, array, boolean, or object matcher.
• Dead Code Elimination (treeshake): Validates tree-shaking properties, such as moduleSideEffects (boolean or array), annotations, or profile strings (smallest, recommended, safest).

A major challenge with online validators is that real-world Rollup configs are JavaScript files, not static JSON files. They contain ES import statements (import resolve from ...), ES module exports (export default { ... }), and run-time plugin invocations (e.g. resolve(), commonjs()).

Our advanced client-side validator uses a specialized JavaScript object normalizer. It identifies standard JavaScript patterns, safely strips comments, replaces function invocations (like plugins and nested instantiations) with static placeholders, and quotes unquoted variables.

This allows you to copy and paste your raw rollup.config.js directly into the validator. The parser will extract the core configuration structure and validate its schema parameters **without executing any arbitrary JavaScript code**, maintaining maximum performance and complete security.

Review the following standard configuration to see what option structures the validator checks:

import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import typescript from '@rollup/plugin-typescript';

export default {
  input: 'src/main.ts',
  output: [
    {
      file: 'dist/bundle.cjs.js',
      format: 'cjs',
      sourcemap: true
    },
    {
      file: 'dist/bundle.esm.js',
      format: 'es',
      sourcemap: 'inline'
    }
  ],
  external: ['react', 'react-dom'],
  plugins: [
    resolve(),
    commonjs(),
    typescript({ tsconfig: './tsconfig.json' })
  ],
  treeshake: {
    moduleSideEffects: false,
    propertyReadSideEffects: true
  }
};

Our validator parses this file structure, replaces plugin calls like resolve() with placeholders, checks the output array, validates that the format values (cjs and es) match standard targets, verifies treeshake keys, and reports a clean, green pass.

Build configurations contain proprietary information, revealing directory structures, build entry points, external dependencies, and internal package names. Sending these configurations to remote servers is a security risk.

Our Rollup Config Validator runs 100% locally in your web browser. All parsing and validation are handled in client-side JavaScript. No file or text content is ever uploaded, stored, or sent across the network. You can validate configuration files completely offline or behind enterprise firewalls, reassuring compliance with security and privacy policies.