Some of the features of Firebug are listed below:
* Inspect HTML and modify style and layout in real-time
* Accurately analyze network usage and performance
* Extend Firebug and add features to make Firebug even more powerful
Get Firebug from here, Compatible with: Firefox 3.5-3.6.
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FirePHP enables you to print to your Firebug Console using a simple PHP function call. All data is sent via a set of X-FirePHP-Data response headers. This means that the debugging data will not interfere with the content on your page. Thus FirePHP is ideally suited for AJAX development.
Pixel Perfect is a firebug extension that allows web developers to easily overlay a web composition over top of the developed html.
YSlow analyzes web pages and tells you why they’re slow based on Yahoo’s rules for high performance web sites. YSlow gives you:
Performance report card
List of components in the page
Tools including JSLint
SenSEO analyzes web pages and tells you how good they fulfill on-page Search Engine optimization criteria. SenSEO is a Firefox add-on integrated with the popular Firebug web development tool. The code is based on the YSlow extension.
A modified version of Firebug optimized for widescreen monitors.
Drupal for Firebug extends Firebug to provide Drupal specific debugging and status messages to help with Drupal development.
7. Page Speed
Firecookie is an extension for Firebug that makes possible to view and manage cookies in your browser
9. CSS Usage
Firebug extension to view which CSS rules are actually used.