Why use terser instead?

terser does AST-aware minification: variable mangling (long names → 1-2 letters), dead-code elimination, constant folding, property name mangling, and more. This tool does textual minification only — typically saves 30-60%; terser hits 70-85% on the same input. For production, always use terser via your build tool.

Will the minified code still work?

Almost always yes for well-formed code. Edge cases that can break: (1) template literals where intra-string whitespace was meaningful (rare), (2) regex literals followed by `/` (rare), (3) ASI-dependent code with no semicolons in unusual places (very rare). Always test minified output before deploying.

What about source maps?

This tool doesn't generate source maps. For debugging-friendly minification, use terser with `sourceMap: true` — it produces a .map file that lets browsers show original line numbers when errors occur in minified code.

Can I minify CSS or HTML with this?

JS-only. CSS minifiers and HTML minifiers exist as separate tools (cssnano, html-minifier-terser). The minification rules differ — CSS allows whitespace minification but has different escape rules; HTML has tag/attribute rules.

What's a bookmarklet?

A small JavaScript snippet stored as a bookmark (URL prefix `javascript:`). When you click the bookmark, the script runs on the current page. Useful for one-click utilities (highlight all links, save to read-later, fill a form). Bookmarklets must fit in one URL — 2,000-32,000 characters depending on browser, so minification matters here.

Will TypeScript or modern JS features break?

TypeScript needs transpilation to JS first (this tool doesn't do that). Modern JS features (optional chaining, nullish coalescing, async/await, top-level await, etc.) generally minify fine — text-based minification doesn't care about feature semantics, just whitespace and comments.

Developer Utilities · Free tool

JavaScript Minifier

Compress JS code by removing comments and whitespace instantly in your browser—free, no-sign-up tool for quick size reduction before production.

Updated June 2026

Input (154 bytes)Minified (100 bytes — saved 54 / 35.1%)

function greet(name){console.log("Hello,"+name+"!");return name.length;}const result=greet("world");

Quick whitespace/comment minifier — strips // … and /* … */ comments, collapses spaces, trims around operators. For production-grade minification (variable mangling, dead-code elimination, AST-aware passes), use terser or esbuild. This tool typically saves 30–60% on hand-written code; minifiers like terser hit 70–85%.

Found this useful?Email Buy Me a Coffee

What it does

Quick text-based JavaScript minifier. Paste a snippet, get back a minified version with whitespace collapsed, comments stripped (both // line and /* block */), and spaces around operators trimmed. Useful for quick one-liners (a function or snippet you want to paste into a constrained context), email and chat embedding where line breaks confuse the receiver, bookmarklet creation (everything has to fit in a single javascript: URL), and quick eyeballing of code size before vs. after minification.

This is textual minification only. For real production minification you want terser (the de-facto standard) or esbuild (faster, integrates with modern build tools). Those do AST-aware optimizations: variable name mangling (renaming userPreferences to a), dead- code elimination (removing if (false) {...}branches), constant folding ( 1+2 → 3 at compile time), property mangling, and tree-shaking unused exports. Textual minification (whitespace + comments) typically saves 30-60%; terser on the same input typically saves 70-85%.

Use this tool when you want a quick one-shot minification without setting up a build pipeline. For your project’s actual production bundle, use Vite/Webpack/Rollup/Parcel which all integrate terser by default.

Embed this tool on your siteShow snippet

Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.

<iframe src="https://freetoolarena.com/embed/javascript-minifier" width="100%" height="720" frameborder="0" loading="lazy" title="JavaScript Minifier" style="border:1px solid #e2e8f0;border-radius:12px;max-width:720px;"></iframe>

Embed docs →

How to use it

Paste your JavaScript code into the input.
The minified version regenerates live as you type, with size before/after and savings percentage shown.
Click Copy to put the minified version on your clipboard.
Test the minified output in a browser console before deploying — textual minification can break code that depends on whitespace (rare but happens with template literals, regex literals, or unusual spacing in object methods).
For production builds, use terser or esbuild via your build tool, not this manual approach.

When to use this tool

Creating a bookmarklet — everything has to fit in javascript:URL within URL-length limits.
Pasting a one-off function into a chat or email where line breaks would mangle it.
Quick size eyeballing — see how much your handwritten code shrinks with whitespace removal.
Inline scripts in HTML attributes (onclick="...") that need to fit in one line.

When not to use it

Production website builds — use terser/esbuild via Vite/Webpack/Rollup. They produce 2× smaller output than text-only minification.
Code with template literals or regex literals where intra-string whitespace matters — text-only minification can corrupt them. AST-based minifiers handle correctly.
TypeScript or JSX — those need transpilation first; this tool is JavaScript-only.
Source-mapped output for debugging — text minification doesn't produce source maps. Real build tools generate maps that let you debug minified code in the original form.

Common use cases

Onboarding a colleague who needs the same calculation/conversion
Verifying a number or output before passing it on
Quick use during a typical workday
Pre-decision sanity-check on inputs and outputs

Frequently asked questions

Why use terser instead?: terser does AST-aware minification: variable mangling (long names → 1-2 letters), dead-code elimination, constant folding, property name mangling, and more. This tool does textual minification only — typically saves 30-60%; terser hits 70-85% on the same input. For production, always use terser via your build tool.
Will the minified code still work?: Almost always yes for well-formed code. Edge cases that can break: (1) template literals where intra-string whitespace was meaningful (rare), (2) regex literals followed by `/` (rare), (3) ASI-dependent code with no semicolons in unusual places (very rare). Always test minified output before deploying.
What about source maps?: This tool doesn't generate source maps. For debugging-friendly minification, use terser with `sourceMap: true` — it produces a .map file that lets browsers show original line numbers when errors occur in minified code.
Can I minify CSS or HTML with this?: JS-only. CSS minifiers and HTML minifiers exist as separate tools (cssnano, html-minifier-terser). The minification rules differ — CSS allows whitespace minification but has different escape rules; HTML has tag/attribute rules.
What's a bookmarklet?: A small JavaScript snippet stored as a bookmark (URL prefix `javascript:`). When you click the bookmark, the script runs on the current page. Useful for one-click utilities (highlight all links, save to read-later, fill a form). Bookmarklets must fit in one URL — 2,000-32,000 characters depending on browser, so minification matters here.
Will TypeScript or modern JS features break?: TypeScript needs transpilation to JS first (this tool doesn't do that). Modern JS features (optional chaining, nullish coalescing, async/await, top-level await, etc.) generally minify fine — text-based minification doesn't care about feature semantics, just whitespace and comments.

Learn more

Explore more developer utilities tools

100% in-browserNo downloadsNo sign-upMalware-freeHow we keep this safe →