@mcp-devtools/bundle-analyzer

MCP server — analyze webpack and Vite bundle sizes, detect duplicate packages, identify tree-shaking opportunities, and compare builds.

Install

npm install -g @mcp-devtools/bundle-analyzer

Generate a stats file

Webpack:

npx webpack --json > stats.json

# For module-level analysis (find_large_modules, detect_duplicate_packages, analyze_tree_shaking):
npx webpack --stats=verbose --json > stats.json

Vite — add rollup-plugin-visualizer to vite.config.ts:

import { visualizer } from 'rollup-plugin-visualizer'

export default defineConfig({
  plugins: [visualizer({ filename: 'stats.json', json: true })]
})

Add to Claude Desktop

~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "bundle-analyzer": {
      "command": "mcp-bundle-analyzer"
    }
  }
}

Restart Claude Desktop after editing the config.

Tools

analyze_bundle

Analyze a webpack stats.json, rollup-plugin-visualizer JSON, or dist/ directory. Auto-detects the format.

path: string  — Path to stats.json, visualizer JSON, or dist/ directory

Returns total size, JS/CSS asset breakdown, top 20 modules by size, and optimization suggestions.

find_large_modules

Find modules exceeding a size threshold. Requires module data (--stats=verbose).

stats_path: string       — Path to stats.json or visualizer JSON
threshold_kb?: number    — Size threshold in KB (default: 50)

Returns modules grouped by vendor vs. app code with import context.

detect_duplicate_packages

Find npm packages bundled at multiple versions. Common when dependencies have conflicting peer requirements.

stats_path: string  — Path to stats.json (--stats=verbose) or visualizer JSON

Returns duplicate packages with all instance paths, wasted size estimate, and fix guidance (npm dedupe, overrides, webpack alias).

analyze_tree_shaking

Identify tree-shaking opportunities: CommonJS modules that can't be eliminated, webpack optimization bailouts, and partially used modules (barrel file suspects).

stats_path: string  — Path to webpack stats.json

For full analysis, set optimization: { usedExports: true } in your webpack config and run with --stats=verbose.

compare_bundles

Diff two builds to measure the impact of a change.

before_path: string  — Path to baseline stats.json
after_path: string   — Path to new stats.json

Returns total JS size diff, changed/added/removed assets with size percentages.

Example prompts

"Analyze the bundle at ./dist/stats.json — what's making it large?"

"Find all modules larger than 100KB in my webpack build"

"Are there duplicate packages in my bundle?"

"Which packages can't be tree-shaken and why?"

"Compare my bundle before and after removing lodash"

Development

npm install
npm run build
npm run dev   # watch mode

License

MIT