Seo Addons for Firefox
The Web Developer extension adds a menu and a toolbar to the browser with various web developer tools. It is designed for Firefox, Flock and Seamonkey, and will run on any platform that these browsers support including Windows, Mac OS X and Linux.

Pulls useful market research data right into Google’s and Yahoo!’s search results, including the following data near each search result.
Google PageRank, Age, Links (Yahoo! Linkdomain), .edu Link (Yahoo! .edu linkdomain), .edu Page Link (Yahoo! .edu link), .gov link (Yahoo! .gov link), Page Links (Yahoo! link), del.icio.us, Technorati, Alexa, Cached, Dmoz, Bloglines, dir.yahoo.com, WhoIs

The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of the browser. It lets you switch / view the current page as in a different browser (IE, Opera, NetScape).

This addon enhances your Google search by giving you more options like search by date (past 24 hours, by week, by month etc), filter by language, search for any file (mp3, doc etc). Pretty effective if you want to save time filtering through results manually.

Display the Google PageRank, Alexa rank, Compete ranking and SEOmoz Linkscape mozRank anywhere in your browser, along with fast keyword density analyser, keyword/nofollow highlighting, backward/related links, Alexa info and more.

6. Google Global Search Plugin
Google Global is an unobtrusive Firefox extension that allows you to see what the Google search results that you are viewing look like from different geographical locations. The easiest way to use Google Global is to simply do a search for something on Google. When you see you search results page, simply right click anywhere on the search results page, select “Search Google Global” and select what geographic location you would like to see the results from. It is as simple as that.

7. K Gen – Keyword Research Firefox plugin
KGen (Keyword Generator) is an extension that allows you to see what keywords are strong on visited web pages. Than, you can retrieve them for social sharing (tag filling) or webmastering/SEO. KGen retrieves every words of a page and lets you know how many time they appears on her and their weight in the page (a word in the title of a page has a stronger weight than a word in a paragraph). So, you can easily know how to optimize your pages, know what’s the secret of your competitors or simply know what’s the main subject of a webpage.

8. yExplore – Yahoo Site Explorer
yExplore adds quick access to search engine & social media information. Just right click, select yExplore and then one of the shortcut links to access information about the site you are viewing. yExplore 2 give quick and easy access to the following information:
Yahoo Site Explorer Backlinks & Inindex, Google Backlinks, Inindex, Cache, Archive.org, Bing Inindex, Delicious saves for a domain, Highlighting of NoFollow links, Check to see if the page you are on is in StumbleUpon, View the Robots.txt file, Spell check the current page, Edit the current page, Text only view, Whois Info

FireShot is a Firefox extension that creates screenshots of web pages (entirely or just visible part). Unlike other extensions, this plugin provides a set of editing and annotation tools, which let users quickly modify web captures and insert text annotations and graphical annotations. Such functionality will be especially useful for web designers, testers and content reviewers.
The captures can be: uploaded to FREE public screenshot hosting, saved to disk (PNG, GIF, JPEG, BMP), printed, copied to clipboard, e-mailed, sent to configurable external editor for further processing.

10. ColorZilla – Pick Color from webpage elements
Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies.With ColorZilla you can get a color reading from any point in your browser, quickly adjust this color and paste it into another program. You can Zoom the page you are viewing and measure distances between any two points on the page. The built-in palette browser allows choosing colors from pre-defined color sets and saving the most used colors in custom palettes. DOM spying features allow getting various information about DOM elements quickly and easily.

11. SearchPreview
Inserts preview images (thumbnails) and popularity ranks of web sites into the Google, Yahoo and Bing search results pages. The SearchPreview thumbnail system currently consists of 9 dedicated servers and generates over 15 TB of traffic per month. For a very few search terms, this version will insert sponsored links into the google.de and google.com search results (labeled as ‘SearchPreview Sponsored Links’). If you don’t like the sponsored links, you can disable them in the SearchPreview options dialog.

12. Alexa Sparky
Sparky is Alexa Internet’s free Firefox plugin. Sparky accompanies you as you surf, providing useful information in your status bar about the sites you visit without interrupting your browsing. Discover website traffic trends, Get detailed traffic information including Reach and Rank , surf more efficiently with Related Links for each page, Gracefully navigate past dead end error pages.

13. Search Cloudlet
Search Cloudlet inserts smart tag clouds into Google / Yahoo / Twitter interface to help you search faster. This free productivity-boosting add-on was featured at LifeHacker, PC World, Website Magazine, etc. Install it now to add magic to your search. One of the most useful features provided by Search Cloudlet is Tag Cloud for search results. Now there is no need to look through results list to understand what it’s all about. Tag Cloud will show you all the keywords relevant to your search results. And you can easily narrow your search by clicking keywords on the cloud and adding/removing them to/from your query.

14. Show IP
Show the IP address(es) of the current page in the status bar. It also allows querying custom services by IP (right mouse button) and hostname (left mouse button), like whois, netcraft. Additionally you can copy the IP address to the clipboard. This extension was formerly known as ipv6ident.

15. Domain Details
Displays Server Type, Headers, IP Address, Location Flag, and links to Whois Reports. Shows links to check server status and cache when page fails to load. View the current site’s server software and headers, IP address, location flag, and have quick links to Whois and other domain information. When a page fails to load, links are shown to check cache and server status.



Comments
Very useful! Thanks a lot
useful,thx for your share!
but I want to add addons to create links with tags in drupal ,did u have any idea.
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It’s great to see what other’s use as tools while working on SEO. This brings a few different things I was doing into one (Firefox).
Thanks for the info.
Its great that you have shared these details. Is there an addon to check bunch of links if the basic SEO strategies are implemented right on that page. It would be very useful if you can share them too.
Thank you