Firebug
Firebug is an excellent Firefox plugin for web developers. Firebug allows you to view, edit and debug HTML, CSS and Javascript live in the browser for any web page. Firebug intergrates directly into the browser window appearing at the bottom of the screen, but can also be displayed in a separate window.
One of the best features of Firebug is the ‘Inspector’. The ‘Inspector’ allows you find HTML elements within your code and then inspect. It allow you to see all the CSS assoicated with the element, both directly applied and inherited. You can then edit these properties live and see the results of these edits live as well.
Firebug’s visualisation of CSS metrics will measure and illustrate all the offsets, margins, borders, padding, and sizes and show them on screen.
Firebug also lets you debug Javascript in great detail. It gives you detailed information about error, allows you to set watches and breakpoints, log calls to functions, etc… Firebug also let you execute Javascript on the fly from a command line.
Firebug also lets you explore the DOM, find DOM object and quickly edit them on the fly.
Another feature of Firebug is its network monitor. The network monitoring tool let you see the load of time of the components within your page, allowing you to optimize your page quickly and easily.
Firebug is an excellent tool for all web develops, making it quick and easily to debug problems with both layout and scripting.
Get Firebug today at http://www.getfirebug.com/