Install them, configure them to recognize the web browsers on your computer (Firefox, Chrome, Opera, Safari, & IE if you use Windows), & set them as the default web browser on your computer. Windows: I've never used it, but it appears that you want Browser Chooser.It's not as slick, but it works with Mountain Lion, & it's free (although I was happy to pay the $12 for Choosy) Mac OS X: I used to really love Choosy, but ever since Mountain Lion, it's been broken.With a browser selection tool, you can! Here are my recommendations: Wouldn't it be nice if I could choose between browsers on the fly, as needed? In Mac OS X, as in Windows and Linux, I can specify a default browser for my system, but that browser is used for everything. In fact, sometimes I'll click on a link and want to open it in Safari, because I want to print the page and I find Safari does that better than any other browser, but a few minutes later I'll click on a link and want to open it in Firefox, because I have that browser set up to handle downloading music and movies. I keep several web browsers on my Mac at all times, and I like to switch back and forth between them.

In my my book, Mac OS X Snow Leopard for Power Users, I explained it this way: To make your life easier, you need to install a browser selection tool. Since you're a web developer, you're going to (a) have more than one web browser on your computer, & (b) want to test your work in more than one browser. Some text editors (BBEdit, for instance) have a feature that lets you open your page in a browser, but Sublime Text does not. Say you're coding HTML in Sublime Text & you want to check how it looks in a browser.

Mac html editor with live preview