JavaScript Minifier

Key features

• Runs the industry-standard Terser parser and printer locally in your tab — the same engine behind most production build pipelines.
• Two independent switches: Compress (dead-code removal, constant folding, boolean simplification) and Mangle (shorten local variable names).
• Your code is treated strictly as data: it is parsed and re-printed, never evaluated, so minifying cannot run it.
• Syntax errors surface as a friendly red panel carrying Terser's message with line and column — no crash, input preserved.
• Size accounting in real byte terms: original, minified, saved and percentage, with a .js download of the result.

How it works

1. 1

   Paste your JavaScript

   Scripts, modules, library snippets — anything syntactically complete. The Terser bundle loads on demand the first time you press the button.

2. 2

   Choose compress and mangle

   Keep both on for the smallest output. Turn mangle off if you need to debug the result against original variable names, or compress off for a comments-and-whitespace-only pass.

3. 3

   Minify and collect

   Press Minify JavaScript, wait for the spinner, then copy the output or download minified.js.

Tips for better results

• 💡Mangling renames local variables only — global names, property names and strings are preserved, which is why the output stays behaviour-compatible.
• 💡If minification reports a syntax error at a line you didn't expect, check for a stray character earlier in the file: parsers fail at the first token they cannot accept.
• 💡For already-minified vendor bundles, a compress+mangle pass usually gains only a few percent — the big wins are on readable source.

Frequently asked questions