Colorzilla – Colorzilla allows you to capture the hex code (e.g #FFF000) of any color you see on the web. This allows you to match colors and grab the exact code of colors you like on other sites. When also used in combination with Adobe Kuler, Colorzilla cures Kuler’s problem of not displaying HTML codes for the selected colors.
Foxmarks – Foxmarks replaces your traditional bookmarking capabilities with synchronized bookmarks. Foxmarks synchronizes your bookmarks with an online account and any computer you install the addon to automatically whenever you close your browser. It takes about two seconds and guarantees that you’ll never be without your bookmarks, whether at a public computer or at home.
Google Toolbar – Google Toolbar is rather simplistic but adds some much needed features to my browser. First, it can replace the standard Firefox search with Google search which is a bit cleaner to look at. Second, it adds a Gmail notifier that lets me know whenever I have new mail with a simple icon. It also adds quick links to some Google services I use often such as Google maps.
Window Resizer – Working as a web developer, it’s important to view my sites in different browsers and different screen resolutions. Window Resizer emulates different screen resolutions be resizing the browser window to different sizes (e.g. 800×600).
Firebug – Firebug is, in my opinion, the most useful addon for a Firefox-based web developer. You can edit your HTML from Firebug, find errors, change your CSS and many more options all from one console. I cannot describe Firebug as well as they can, so please take a look at the Firebug site at http://getfirebug.com/
YSlow – YSlow is not an addition to firebug but is integrated with it for information exchange. YSlow analyzes any web page and generates a grade for each rule and an overall grade. If a page can be improved, YSlow lists the specific changes to be made. YSlow is especially useful on high traffic sites where limiting the number of HTTP requests makes more of a difference but has great suggestions for smaller sites as well.
Colorful Tabs – Colorful tabs doesn’t have any big use in web development but it speeds up my overall surfing. Tabs can be colored by many different options allowing you to find important sites at a glance or just to differentiate between tabs easier.
What addons are indispensable to you?