JS/CSS Minifier
JS/CSS Minifier — runs in your browser. Inputs are not stored.
Basic JS / CSS minify
Enter values, then press Calculate.
Simply strips comments and whitespace. Not a substitute for advanced obfuscation or a bundler.
How to use
- Under mode, choose JavaScript or CSS. Default is JavaScript.
- Paste code to minify in source.
- Press Minify. Code with comments and whitespace reduced appears in result.
- In the stats above, compare original and minified character counts.
- Copy result takes it. Reset resets source, result, and numbers, and restores mode to JavaScript.
Key concepts
JS/CSS minify is a light shrinker that strips comments and whitespace to shave a little size just before deploy. JavaScript mode removes block and line comments and glues spaces around braces and operators; stylesheet mode removes block comments then glues spaces between selectors and braces. It does not obfuscate names, tree-shake, or analyze scope, so it does not replace a bundler or Terser. It is suited to eyeballing bytes on a small snippet.
Original and minified numbers are input/output string lengths. Slashes in regex literals or comment-like patterns inside strings can be misread, so complex source is safer minified in a build pipeline. JS/CSS minify does not upload files; it only substitutes in the browser. It is not a production-bundle quality tool, but a helper to shorten a comment-heavy draft and compare. If minified output looks broken, check the mode, and keep your existing bundle settings for the final deploy copy. After you eyeball the size difference on a short function or one block of rules, copy it.
Example
In JavaScript mode, paste function hello() { /* greet */ console.log("hi"); } and minify: comments and whitespace disappear and it glues toward one line. Original and minified character counts update in the stats.
Related: JS/CSS formatter · HTML formatter · JSON formatter
Frequently asked questions
Is JS/CSS minify the same as a bundler or Terser?
No. It only strips comments and whitespace with regex. It does not shorten variable names or remove dead code.
Why split JavaScript and CSS modes in JS/CSS minify?
JavaScript handles line comments and operator spacing; stylesheets treat selector/brace spacing and extra semicolons differently.
What are the original and minified numbers after JS/CSS minify?
They are character counts of the input source and output result. They show shrinkage as string length, not kilobytes.
Can comment-like symbols inside strings break JS/CSS minify?
Yes. Simple substitution can mistake // inside a regex or string for a comment, so use a dedicated minifier for important source.
Is JS/CSS minify source uploaded to a server?
No. Minify, copy, and reset all finish in the browser. There is no file upload.
Does JS/CSS minify Reset change the mode too?
Yes. It sets source, result, and original/minified numbers back to 0 and restores mode to JavaScript.
Last reviewed: 2026-09-04