I've been using Firebug for years and it's been a great tool for debugging and tinkering with web-based code. It's easy to use, and the code inspectors and debugger make it easy to quickly identify and fix any issues. The command line is also very useful for quickly testing out new code. Highly recommend Firebug for anyone who needs to work with web-based code.
Firebug 2.0.19 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The program lies within Internet & Network Tools, more precisely Browser plugins.
We recommend checking the downloaded files with any free antivirus. The following versions: 2.0, 1.9 and 1.5 are the most frequently downloaded ones by the program users. This free software is an intellectual property of Mozilla Inc. Firebug.exe is the most frequent filename for this program's installer.
From the developer:
Firebug integrates with Firefox to put a wealth of web development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
Firebug is always just a keystroke away, but it never gets in your way. You can open Firebug in a separate window, or as a bar at the bottom of your browser. Firebug also gives you fine-grained control over which websites you want to enable it for.
You may want to check out more software, such as HTTPA Reader, Companion.JS for Internet Explorer or SWFWire Debugger, which might be related to Firebug.
Browser extensions