Firefox addons which are useful for search engine optimization while searching / browsing.

Foxy SEO Tool – Foxy SEO Tool is a free, open source toolbar that provides quick and easy access to a multitude of search engine functions such as Google Site, Yahoo! Site Explorer, Live Fromlinks. Also included are famous web traffic analysis sites such as Alexa, Compete, Quantcast, popular statistic aggregators like Quarkbase and WebSiteOutlook. You can check a site’s listing in important directories like Dmoz and Yahoo! Directory, buzzing Web 2.0 sites such as Technocrati, Wikipedia, Digg, Delicious and links to useful network functions like Whois, Geotool, Internet Archive, etc.

RankQuest SEO Toolbar – This toolbar provides you quick access to more than 30 intuitive SEO tools. Alexa Rank and Page Rank provided by Alexa and Google respectively ensures the popularity of the site. Once you download and install the SEO Toolbar you are only one or two clicks away from carrying out most of your day to day SEO operations.

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mod_expires – This module controls the setting of the Expires HTTP header in server responses. The expiration date can set to be relative to either the time the source file was last modified, or to the time of the client access.

The Expires HTTP header is an instruction to the client about the document’s validity and persistence. If cached, the document may be fetched from the cache rather than from the source until this time has passed. After that, the cache copy is considered “expired” and invalid, and a new copy must be obtained from the source.

mod_expires is included in most default installs.

Check wheter LoadModule expires_module modules/mod_expires.so is enabled or not in httpd.conf, if its not then uncomment it removing the # prefix.

And then add following code into your httpd.conf configuration file -

Restart apache server.

Resource links -

http://blog.cherouvim.com/mod_expires-and-cache-killers/
http://httpd.apache.org/docs/1.3/mod/mod_expires.html
http://www.david-guerrero.com/papers/squid/squid.htm
http://linuxreviews.org/webdesign/602_Apache_mod_expire/
http://jeremy.zawodny.com/blog/archives/009272.html

Web Developer

The Web Developer extension adds a menu and a toolbar with various web developer tools.
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ColorZilla

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.
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