While there are plenty of more comprehensive lists out there, there are a few tools I use for web development on a daily basis that are worth talking about.
The number one is obviously Firebug. Doing web development without is like developing with a rock on an etch-a-sketch.
Some favorite features
Easily print messages to the Firebug console.
View (and even modify) HTML and CSS in a nice structured way.
View network activity and page speed using the Net panel. You can get more page speed information using YSlow or PageSpeed.
FirePHP is a plugin for Firebug that lets you log messages to the Firebug console using server-side PHP calls. Fantastic for simple debugging. SixRevisions has an excellent guide on setting it up.
Web Developer tools
This is another must-have with too many features to list. Some of my favorites are:
- Easily clear domain, url, & session cookies for the current page.
- Turn styles on and off.
- Automatically populate HTML form fields.
- Lots of information about how elements are rendering on the page.
A handy Firefox add-on that automatically validates the HTML of a page. It also improves Firefox's "View Source" interface.
Nice, stand-alone desktop app for measuring pixel distance.
Great desktop app from Iconico for picking colors from the screen. Also handy as a general purpose screen-zoom tool.
I'm sure people out there have their own favorite tools and I'd love to hear about them.