Page Analysis & SEO

About This Site Bookmarks – right-click on a page, select “About This Site Bookmarks” and you will see a list of handy links pointing off to informational sites such as Alexa, Compete, Netcraft, del.icio.us, etc.

SearchStatus

ShowIP

Minimising Nuisance

Adblock Plus

Adblock Filterset.G Updater

Bookmark Management

Add Bookmark Here

Bookmark Duplicate Detector

del.icio.us

Download Management

Download Statusbar – manage your downloads via the Firefox status bar.

DownThemAll – conveniently download all link targets on a page.

FlashGot – allows for single and multiple downloads utilising an external download manager of your choice (I prefer FlashGet).

Productivity

Auto Copy – highlight a piece of text and the selection is automatically copied to your clipboard.

FoxClocks – displays local times around the world in the statusbar or toolbar. Great for if you are dealing with friends and colleagues across multiple timezones.

FoxyTunes – operate your currently running media player from your Firefox statusbar.

Google Notebook – conveniently clip text and links to your Google Notebook.

Linkification – Converts text links (including e-mail addresses) into clickable links.

PDF Download

Web Development & Design

ColorZilla – eye-dropper tool that allows you to pick the HEX & RGB values of colours of elements on the page.

Firebug – the quintessential Javascript debugger. It also allows for excellent DOM and CSS debugging and manipulation.

HTML Validator

IE View – open the current page in an IE window.

Live HTTP Headers – view HTTP request and response headers in realtime.

User Agent Switcher – allows you to spoof the User-Agent string and have Firefox masquerade as the Googlebot, etc, to see how your site reacts to different user-agents.

View Source Chart – renders page source HTML in an easy-to-read manner.

Web Developer – a must for the serious web developer.

YSlow – an addon to the Firebug debugger. It allows you to profile a page and identify bottlenecks. Provided by Yahoo. Also see Yahoo’s articles on improving page load performance.

Security

CookieSafe

Edit Cookies

McAfee SiteAdvisor – lets you know if the currently viewed site is considered “safe” or not.

Functionality Extensions

CustomizeGoogle – customize your Google search and application experiences.

ErrorZilla – extends the standard page not found error screen with convenient links such as access to the page’s Google cached copy.

Secure Login

View Cookies

Tab Management

Faviconize Tab – minimize a tab’s width to the width of the favicon.

Tab Mix Plus

Add-Ons Management

Google Browser Sync

FEBE – a convenient extensions & settings backup tool. Allows you to also run scheduled backups. The backups can be used to transport your extensions and their settings to another machine or Firefox profile.

MR Tech Local Install – install power tools for add-ons