Conservative and predictable
Only comments and whitespace that cannot change behaviour are removed. Variable names, function names and string contents are untouched, so the output is easy to reason about.
DeveloperRuns in your browser
JavaScript Minifier
Remove comments and whitespace from JS without renaming identifiers.
- Input
- No upload needed — instant
- Privacy
- Nothing is uploaded
- Cost
- Free · no sign-up · no watermark
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Processed entirely on your device
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Overview
About the JavaScript Minifier
Minify JavaScript online with a conservative pass that strips comments and insignificant whitespace without renaming identifiers or altering behaviour. In-browser, no upload.
There are two things people call JavaScript minification, and it is worth being clear about which one this is. A full minifier parses your code into an abstract syntax tree, renames every local variable to a single letter, folds constants, drops unreachable branches and re-emits the smallest equivalent program. This tool does the safe half of that job: it removes comments and whitespace that cannot change what the code does, and leaves everything else exactly as you wrote it.
Why conservative is a feature
Renaming identifiers is powerful but fragile. It breaks code that reads function.name, that relies on a variable name matching a string used in reflection or dependency injection, or that shares a global with another separately minified file. A whitespace-only pass has none of those failure modes. The output is still recognisable, still debuggable and still greppable, which is exactly what you want for a snippet you are about to paste somewhere and forget.
What it removes and what it keeps
The kept column is the hard part. A regular expression such as one matching a space, or a template literal spanning several lines, contains whitespace that is data rather than formatting. Stripping it would silently change behaviour, so the pass tracks those contexts and leaves them alone.
Automatic semicolon insertion
JavaScript infers semicolons from newlines in a few situations. Joining two lines carelessly can move where a statement ends and change the program. This is the classic reason a find-and-replace on newlines is not a minifier. A correct pass knows where a line break is load-bearing and keeps it, which is why the reduction is smaller than a real compiler achieves but the result is trustworthy.
When to reach for a real bundler
For an application, use Terser, esbuild or SWC in your build. They produce source maps so minified stack traces still point at your original lines, and their renaming and tree-shaking cut far more than whitespace removal can. Use this tool for the small jobs: compressing an inline script, shrinking a bookmarklet, or checking how much of a file is just formatting.
Step by step
How to use the JavaScript Minifier
Paste your JavaScript into the input panel.
Press Minify JavaScript; comments and insignificant whitespace are removed.
Review the output — identifiers and logic are left exactly as written.
Copy the result or download it as a .js file.
Why use it
Benefits and common use cases
What this tool is good for, and what it deliberately does not try to do.
No renaming surprises
Because it never mangles identifiers, it cannot break code that relies on function.name, reflection, or names referenced across separately loaded files.
String and regex safe
Whitespace inside string literals, template literals and regular expressions is preserved, which is where a naive whitespace-stripping pass corrupts code.
Runs entirely in your tab
Proprietary or unreleased scripts are never sent to a server — the whole pass happens in the browser.
Questions
Frequently asked questions
Short, honest answers about quality, limits and privacy.
Does this rename variables like UglifyJS or Terser?
No. This is a whitespace and comment minifier, not a full compiler. It never shortens identifiers, rewrites expressions or performs dead-code elimination. That makes it safe and predictable, at the cost of a smaller reduction than a build-time bundler achieves.
Will minifying change how my script behaves?
It should not. Removing comments and insignificant whitespace does not alter semantics. The only place whitespace matters in JavaScript is inside strings, template literals and regular expressions, and those are preserved exactly.
Why does whitespace sometimes matter in JavaScript?
Automatic semicolon insertion means a newline can end a statement, so a minifier must not join two lines in a way that changes where a semicolon is implied. It also matters inside template literals, where newlines are part of the string, and in regular expressions. A conservative pass keeps those intact.
How much smaller does JavaScript get?
A readable, commented script usually shrinks by 20 to 40 percent with whitespace and comment removal alone. Full minifiers that also rename identifiers and drop dead code can reach 50 to 70 percent, which is why production builds use a real bundler.
Should I use this in production?
For a quick inline snippet or a small standalone script, yes. For an application bundle, use a build-time minifier such as Terser or esbuild that also tree-shakes, mangles names and produces source maps. This tool is best for one-off compression and for seeing exactly what whitespace removal does.