JavaScript Minifier
Minify JavaScript by removing comments, whitespace and dead code. Fetch from URL, upload a file, or use AI-powered optimization.
Free JavaScript Minifier — Reduce JS Bundle Size
JavaScript is one of the heaviest resources a browser downloads for most modern websites. Unminified JS files contain whitespace, comments, long variable names, and formatting that is useful for developers but adds unnecessary bytes for end users. This free JavaScript Minifier compresses your JS code instantly in the browser, reducing file size by 20–50% depending on the original code.
Paste your JavaScript code and click Minify. The tool removes whitespace, line breaks, and comments, and in advanced mode shortens variable names to minimize file size. Copy the result for use in your production build.
In production environments, JS minification is typically handled automatically by build tools like Webpack, Vite, or Rollup. This tool is useful for quick one-off minification, for scripts outside your build pipeline, and for understanding the size reduction potential of your code.
Why JS File Size Matters for Performance
Render blocking. JavaScript in the <head> blocks HTML parsing until it downloads and executes. Smaller files unblock rendering faster.
Time to Interactive. JS execution on the main thread delays interactivity. Smaller bundles execute faster, improving TTI — a key user experience and ranking metric.
Mobile performance. Mobile devices download and parse JS more slowly than desktops. Minimizing JS size is particularly impactful for mobile performance scores.
Core Web Vitals. Total Blocking Time (TBT) and Largest Contentful Paint (LCP) are both negatively affected by large, slow-loading JS files.
Related Tools
- CSS Minifier – Compress CSS stylesheets.
- HTML Compressor – Minify HTML markup.
- Page Speed Checker – Audit overall page performance.
Frequently Asked Questions
What does JS minification do?
Removes whitespace, comments, and renames variables to produce the smallest possible file.
Does it improve SEO?
Yes. Smaller JS = faster TTI + better Core Web Vitals = improved rankings.
Is it reversible?
Basic minification is reversible with a beautifier. Advanced variable renaming requires source maps.
Is this free?
Yes. Free, browser-only processing.