Tool to Unminify / Decompress JavaScript [closed]

Are there any command line scripts and/or online tools that can reverse the effects of minification similar to how Tidy can clean up horrific HTML?

(I'm specifically looking to unminify a minified JavaScript file, so variable renaming might still be an issue.)

You can use this : But it depends on the minify method you are using, this one only formats the code, it doesn't change variable names, nor uncompress base62 encoding.

edit: in fact it can unpack "packed" scripts (packed with Dean Edward's packer :

Chrome developer tools has this feature built-in. Bring up the developer tools (pressing F12 is one way), in the Sources tab, the bottom left bar has a set of icons. The "{}" icon is "Pretty print" and does this conversion on demand.

UPDATE: IE9 "F12 developer tools" also has a "Format JavaScript" feature in the Script tab under the Tools icon there. (see Tip #4 in F12 The best kept web debugging secret)

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Got it! JSBeautifier does exactly this, and you even have options for the auto-formatting.

Can't you just use a javascript formatter ( ?

In Firefox, SpiderMonkey and Rhino you can wrap any code into an anonymous function and call its toSource method, which will give you a nicely formatted source of the function.

toSource also strips comments.

E. g.:

(function () { /* Say hello. */ var x = 'Hello!'; print(x); }).toSource()

Will be converted to a string:

function () {
    var x = "Hello!";

P. S.: It's not an "online tool", but all questions about general beautifying techniques are closed as duplicates of this one.

If you have a Mac and TextMate - An easy alternative for formatting Javascript is:

  1. Open the file with Textmate.
  2. Click on > Bundles > JavaScript > Reformat Document
  3. Crack open a beer.

Most of the IDEs also offer auto-formatting features. For example in NetBeans, just press CTRL+K.

As an alternative (since I didn't know about until now), I have used a bookmarklet that reenabled the decode button in Dean Edward's Packer.

I found the instructions and bookmarklet here.

here is the bookmarklet (in case the site is down)


I'm not sure if you need source code. There is a free online JavaScript formatter at

Try this one, with code coloration:

click on these link for JS deminification. That will install on FF as extension that help you in debugging js at runtime.

Similar to Stone's answer, but for Windows/.NET developers:

If you have Visual Studio and ReSharper - An easy alternative for formatting Javascript is:

  • Open the file with Visual Studio;
  • Click on ReSharper > Tools > Cleanup Code (Ctrl+E, C);
  • Select "Default: Reformat code", and click OK;
  • Crack open a beer.

Despite its miles-away-from-being-pretty interface, JSPretty is a good, free and online tool for making javascript source codes human-readable. You can enforce your preferred type of indentation and it can also detect obfuscation.

If one is in JS possibility of using Firefox is more. And if its Firefox add on is for rescue. Following one is particularly useful.

Pretty Diff will beautify (pretty print) JavaScript in a way that conforms to JSLint and JSHint white space algorithms.

Wasn't really happy with the output of for what I was putting in, so I did some more searching and found this site:

Worked extremely well for me. Great tools for unminify javascript and json