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Analyze JavaScript bundle size impact with raw bytes, gzip estimate, and brotli estimate in one view.
Raw Size
0 B
Gzip Size
N/A
Brotli Size
N/A
Gzip uses browser CompressionStream. Brotli is an approximate estimate from gzip for quick budgeting.
All JavaScript processing runs locally in your browser. No code uploads.
Bundle size is one of the most impactful factors in web performance. The Bundle Size Analyzer lets you inspect JavaScript package sizes, understand dependency weight, and identify bloated imports — all without installing anything or uploading your code.
Google recommends keeping total JavaScript under 300 KB gzipped for mobile-first sites. Use this tool to audit each dependency before adding it to your project — a 50 KB library may seem small until you have 20 of them.
Replace moment.js (300 KB) with date-fns (tree-shakeable, ~7 KB per function). Replace lodash (72 KB) with lodash-es for tree-shaking. Use native fetch instead of axios (13 KB) when possible.
Size estimates reflect the published npm package after minification and gzip. Actual impact in your bundle may differ based on tree-shaking, build tool configuration, and which specific exports you import.
Google recommends under 300 KB gzipped for mobile-first sites. For desktop-focused apps, up to 500 KB gzipped is reasonable. Each additional 100 KB of JS adds roughly 0.5-1 second to parse time on mid-range mobile devices.
Use tree-shakeable imports (import { specific } from library), replace heavy libraries with lighter alternatives, lazy-load non-critical code with dynamic imports, and audit your dependency tree for duplicates.
Check out our technical guides to learn more about how browser-side processing works.
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