Optimize and compress JavaScript code to reduce file size and improve website performance. This free online JavaScript optimizer uses Terser, the industry-standard minification tool, to minify, compress, and optimize your JS code for production deployment. All processing happens entirely in your browser using JavaScript - your code never leaves your device, ensuring complete privacy and security.
Faster Page Load Times
Smaller JavaScript files download faster, especially on mobile networks or slow connections. By reducing your JS file size by 40-60%, you significantly improve page load times and user experience. Every kilobyte saved means faster downloads and quicker script execution.
Improved Website Performance
Modern websites often include hundreds of kilobytes of JavaScript. Optimizing your code reduces the amount of data browsers need to download, parse, and execute. This leads to better performance scores in tools like Google Lighthouse, PageSpeed Insights, and WebPageTest.
Better SEO Rankings
Google considers page speed as a ranking factor. Faster-loading pages rank higher in search results. By optimizing JavaScript files, you reduce load times and improve Core Web Vitals metrics, which directly impact your SEO performance.
Reduced Bandwidth Costs
For high-traffic websites, smaller files mean lower bandwidth usage and reduced hosting costs. If your site serves millions of requests, optimizing JavaScript can save significant money on CDN and bandwidth expenses.
Production Deployment
Before deploying to production, optimize all JavaScript files to reduce load times. This is standard practice for professional web development. Most build tools (webpack, vite, rollup) use Terser internally for production builds.
Single-File Projects
For simple projects without build tools, use this online optimizer to prepare JavaScript files for production. Upload your script, optimize it, and download the minified version ready for deployment.
Quick Testing
Test how much smaller your code becomes after optimization. See the impact of different optimization options and find the best balance between file size and readability.
Learning and Teaching
Understand how minification works by seeing the before/after results. Learn about dead code elimination, variable mangling, and other optimization techniques used in professional development.
After optimization, you'll see detailed statistics:
Q: Is my code safe when using this tool?
A: Yes! All JavaScript optimization happens entirely in your browser using the Terser library. Your code never leaves your computer and is never uploaded to any server. We don't store, log, or transmit your code in any way. This makes our tool completely safe for proprietary code, client projects, or sensitive scripts.
Q: Will optimization break my code?
A: Terser is battle-tested and used by millions of developers in production. It's the same minifier used by webpack, Next.js, and other major tools. However, always test optimized code before deploying. Some edge cases (like code relying on specific function names) may need adjustments.
Q: What's the difference between minification and optimization?
A: Minification removes whitespace and shortens code. Optimization goes further by removing dead code, simplifying expressions, and making the code more efficient. This tool does both - minifying for size and optimizing for performance.
Q: Can I reverse the optimization?
A: No, minification is one-way. Variable names are lost during mangling. Always keep your original source code. Use this tool only on copies destined for production, never on your only copy of the code.
Q: How much smaller will my code be?
A: Typical reduction is 40-60% for well-formatted code with comments. Code that's already compact may see less reduction. Code with extensive comments and whitespace may see 70%+ reduction.