Google Code Project: http://code.google.com/p/burp-suite-beautifier-extension/
Most of the websites compress their resources such as JS files in order to increase the loading speed. However, security testing and debugging a compressed resource is not an easy task. This is a Burp Suite open source extension which makes it possible to beautify most of the resources properly. Therefore, it will help the web application security researchers to view the compressed resources easier. It also helps them to have the decompressed versions of the resources (such as JS, CSS, HTML, XML, and so on) inside the browsers to debug them without any problem.

Features:
1- Manual beautifying the requests/responses
2- Automatic beautifying the responses in the scope of proxy
3- Syntax highlighter in the read-only editor

This extension is based on the following modules/libraries:
1- JS files of http://jsbeautifier.org/ – Written by Einar Lielmanis, einar@jsbeautifier.org
2- Rhino: JavaScript for Java – http://www.mozilla.org/rhino/
3- Fifesoft RSyntaxTextArea – http://fifesoft.com/rsyntaxtextarea/

Limitation:
1- Limitations of jsbeautifier.org
2- Only support UTF-8 for texts

Using the application:
1. Download the zip file and extract it in root of the Burp Suite folder. Now, you should have a folder with three jar files and a batch file outside of this folder.
2. Use “beautifier.bat” to run the Burp Suite application. In this file, “burpsuite_pro.jar” is the name of your Burp Suite jar file. You can also change the Java allocated memory if you experienced any problem. Or, run it via command line directly:
java -Xmx512m -classpath burpsuite_pro.jar;./beautifier/beautifier.jar;./beautifier/js.jar;./beautifier/rsyntaxtextarea.jar burp.StartBurp
3. Now if you right click on a request or response, you should be able to see these options: “Beautify This!” and “Beautify All Responses in Scope” (the automated one only works in the “proxy” section to prevent from any performance issue)

Reporting the issues:
Please report the issues via the google code link. Please make sure that it is not an external library bug before reporting it here.

Tested on:
This extension has been tested on Burp Suite Free 1.4.01 and Burp Suite Pro v1.4.07 with Java v7u4. It should work in other versions.

Download the project:
Please get it from the Google Code page: http://code.google.com/p/burp-suite-beautifier-extension/