When I talk to testers about the tools I find useful for testing I always end up talking about Firefox. If you are testing a web-based application, you owe it to yourself to get up to speed on Firefox-the-tool as compared to Firefox-the-browser.

The power of Firefox is in its extension ecosystem. Here are the ones I have installed, though I am sure there are other interesting ones that I haven’t discovered.

  • Web Developer – Clearing your cookies from the toolbar is worth this extension alone but you can also validate your html/css and highlight certain elements on the page.
  • Firebug – Firebug is likely the single most useful plugin for Firefox. I use it to troubleshoot html generation and css rendering issues as well as checking for proper form validation by removing client-side validation from the rendered page. It will also show you the XPath location for items on the screen if you are using that in your automation setup.
  • YSlow – YSlow is a plugin for Firebug which ranks your page based on a set of heuristics that were learned by people at Yahoo and later in a (couple of) books. I’m less hot on this than I was a year ago though as a lot of sites don’t need all the things it suggests; like a CDN. It is still a useful tool for a suggestion perspective though.
  • Live HTTP headers – Right after Firebug, Live HTTP headers is plugin I install. It lets you see the non-rendered communication between the browser and the server; cookies, expiration headers, etc. There are a tonne of testing possibilities once you can see this exchange.