What should I use for production instead?

esbuild, Terser or SWC, run as part of your build. All three parse the code into a syntax tree first, which is what lets them rename variables, drop dead branches and join lines safely — savings of 60-70% rather than the 20-30% available from whitespace alone. This page is for the cases with no build step: an inline script, a CMS field, a bookmarklet.

How much smaller will my file get?

Usually 20-30% for well-commented source, and almost nothing for code that has already been through a bundler. The figure reported under the result is the real one for your file. Note that gzip, which every web server applies, already compresses repeated whitespace very efficiently — so the saving over the wire is smaller than the saving on disk.

Are my strings and regular expressions safe?

Yes. The scanner identifies strings, template literals, regular expressions and comments before touching anything, so `const s = " // not a comment "` keeps its spaces and its slashes. Only whitespace in actual code positions is removed.

JavaScript Minifier

Remove the comments and indentation from JavaScript to make it smaller. This one is deliberately conservative, and it is worth knowing why: joining two lines of JavaScript can change what the code does, because of automatic semicolon insertion. A `return` with its value on the next line returns undefined; put them on one line and it doesn't. Getting that right requires a full parser, so this tool removes what it can remove safely and keeps every line break.

Your text

Result

Nothing is uploaded — this tool runs inside your browser, so your files never leave your device.

Help us improve

Why use this tool

Removes comments and all leading and trailing whitespace
Keeps line breaks, so automatic semicolon insertion cannot change behaviour
Never touches the inside of a string, template literal or regular expression
Reports the before and after size, and the percentage saved

How it works

1Paste the JavaScript you want to shrink.
2Copy the result, or download it as a file.
3For production, use a real bundler — see the answer below.

JavaScript Minifier — frequently asked questions

Because doing that safely requires parsing the code, and doing it unsafely silently breaks it. JavaScript inserts semicolons at line ends under specific rules, so removing a line break can change the meaning of the program — most famously with `return`, where the value on the next line is simply discarded once they are joined. Removing comments and indentation is the largest saving available without that risk.

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