Free JavaScript Minifier

The JavaScript Minifier is a free online tool that compresses JavaScript code by removing whitespace, shortening variable names, and eliminating comments to reduce file size.

Yes, it is completely free with no registration required. All minification happens client-side in your browser.

No, the JavaScript Minifier preserves functionality while reducing file size. The minified code runs identically to the original.

Absolutely. The JavaScript Minifier processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the JavaScript Minifier is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the JavaScript Minifier in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The JavaScript Minifier works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

Minification and gzip solve the same problem in two stages. Minification rewrites the source itself: it strips comments, whitespace, and newlines, and can shorten variable names so the file holds the same logic in fewer characters. Gzip (or Brotli) is a compression algorithm your server or CDN applies on top of the response as it travels to the browser, where it is automatically decompressed. The two stack: minified code gzips better because it has less redundant formatting for the algorithm to encode. That's why minify first, then let the server gzip. This tool does the first step in your browser and also estimates the gzip transfer size, so you see both the raw minified size and the smaller figure that actually reaches your users. Paste your script above to compare original, minified, and gzip sizes side by side.

The three presets trade compression for risk. Safe is the most conservative: it strips comments and collapses whitespace and newlines but leaves your logic completely untouched, so it's the right choice for code you can't fully retest. Production runs the Safe pass and adds deploy-oriented cleanup: removing console and debugger statements and simplifying expressions, producing output ready to ship. Maximum chases the smallest possible file: on top of Production it drops optional semicolons, shortens local variable names, and removes unused variable declarations. The more aggressive the preset, the more the code changes, so retest after using Maximum. Every preset is just a starting point: a panel of individual toggles lets you mix passes by hand, like keeping comments but mangling variables. Pick a preset above, then fine-tune the toggles to match how much you're willing to change.

Variable name shortening, often called mangling, replaces long descriptive names like userAccountBalance with one- or two-character names such as a or b. Those names exist only to help humans read the source; the browser doesn't care what a local variable is called, so renaming it has no effect on how the code runs as long as scope is respected. Shorter names mean fewer characters to download and parse, which adds up across hundreds of references in a real script. The minifier only mangles local variables, leaving globals and anything other code might reference by name intact, so behavior stays the same. Mangling is included in the Maximum preset and available as its own toggle, and the results panel reports how many variables were shortened. Enable variable shortening above when you want the smallest output and can retest the result.

Minified code is almost impossible to debug directly: variables are renamed, lines are collapsed, and a stack trace points to column 4,000 of a single line. A source map is a separate .map file that records how each piece of the minified output maps back to your original source. When the browser dev tools load it, errors and breakpoints show up against your readable, original code instead of the compressed blob, so you can debug production output as if it were never minified. You reference the map with a comment at the end of the file or an HTTP header, and you typically keep it out of the public download so visitors don't ship it. This tool can generate a source map alongside the minified script as an optional output. Turn on the source map option above before minifying if you plan to debug the result later.

By default, minification strips every comment, since comments add bytes without affecting how the code runs. That's a problem when a dependency's license requires its attribution banner to stay in the file, because deleting it can breach the license terms. The convention is to mark those comments specially: a block comment that starts with /*! or one that contains an @license or @preserve annotation signals "keep me." This tool has a preserve-license option that keeps exactly those banner comments intact even under the aggressive Maximum preset, while still removing ordinary explanatory comments. So you get the smallest file that's still legally clean to redistribute. Enable the preserve-license toggle above before minifying any code that bundles third-party libraries, then check that the banner still appears at the top of the output.