Skip to main content
SlapMyWeb
Get started
Skip to tool
Developer tools/All tools
Free tool

JavaScript minifier

Minify JavaScript by stripping comments, collapsing whitespace and compressing code for production. Reduces bundle size instantly.

minified
javascript
No output yet

What is JavaScript Minifier?

A JavaScript minifier is a build optimization tool that reduces the file size of your JavaScript code by removing everything that is not needed for execution. This includes single-line comments (//), multi-line comments (/* */), excess whitespace, line breaks, and unnecessary spacing around operators and punctuation. The result is a compact, single-line script that browsers parse and execute faster. Minified JavaScript directly improves page load performance by reducing download size and parse time, which positively impacts Core Web Vitals metrics like First Contentful Paint (FCP) and Time to Interactive (TTI). Professional build tools like Webpack, Vite, and Rollup include minification as a production step, but this free online JavaScript minifier lets you quickly compress individual scripts without setting up a build pipeline. All processing happens in your browser — nothing is uploaded to a server, so your source code stays completely private.

How to Use JavaScript Minifier

  1. 1

    Paste your JavaScript source code

    Copy your JavaScript code from your editor or file and paste it into the input field. The tool accepts any JavaScript including functions, classes, modules, and ES6+ syntax.

  2. 2

    View the minified output

    The minified result appears instantly below the input. Single-line and multi-line comments are stripped, whitespace is collapsed, and operator spacing is compressed into the smallest possible output.

  3. 3

    Check savings and copy

    Review the character count comparison showing original size, minified size, and percentage saved. Click Copy to grab the minified code for use in your production build or CDN deployment.

Features

  • Strips both single-line (//) and multi-line (/* */) comments
  • Collapses all whitespace including tabs and newlines into minimal spacing
  • Compresses operator spacing around braces, parentheses, and semicolons
  • Shows exact character count savings with percentage reduction
  • Processes code instantly as you type with zero latency
  • Runs entirely client-side — source code never touches a server

Related Tools

JSON Formatter & Validator

Pretty-print and validate JSON with 2 / 4 space indentation.

Open tool

JSON to CSV Converter

Convert JSON arrays to CSV format. Auto-detects columns, proper escaping, download as .csv.

Open tool

CSV to JSON Converter

Convert CSV data to a JSON array of objects. Handles quoted fields and commas.

Open tool

HTML Formatter & Minifier

Beautify messy HTML with proper indentation or minify it for production.

Open tool

HTML Minifier

Minify HTML by stripping comments, collapsing whitespace. Shows size savings.

Open tool

CSS Formatter & Minifier

Beautify CSS with proper indentation or minify it for production. Strips comments.

Open tool
See all Developer tools

Frequently Asked Questions

Will minifying my JavaScript break anything?+
Basic minification (comment and whitespace removal) does not change code behavior. However, if your code relies on Function.toString() or eval parsing, the changed formatting could theoretically cause issues. Standard applications are not affected.
How is this different from uglification or obfuscation?+
Minification removes comments and whitespace but keeps variable names and code structure intact. Uglification (like Terser) also shortens variable names and applies code transformations. Obfuscation intentionally makes code hard to reverse-engineer. This tool performs minification only.
Can I minify TypeScript with this tool?+
This tool processes JavaScript, not TypeScript. You should compile TypeScript to JavaScript first using tsc or your build tool, then minify the resulting JS output.
What percentage of file size reduction should I expect?+
Typically 30-60% reduction depending on how heavily commented and formatted the original code is. Well-documented code with JSDoc comments often sees the highest savings.
Should I minify JavaScript before or after bundling?+
In professional workflows, minification is usually the last step after bundling. Bundle your modules first (with Webpack, Rollup, or Vite), then minify the output bundle. This tool is useful for quick one-off minification of individual files.
Is the minified output safe to use in production?+
Yes. The minification only removes non-functional content (comments and whitespace). The output is semantically identical to your input and safe for production deployment.