Web Applications
The Google Keyword Tool is by far the most useful Free keyword research tool available, it not only shows search volumes but also how difficult the competition is.Google Webmaster Tools
Webmaster Tools is perfect for checking keywords you may be ranking for but didn’t know about and also for checking that you have no crawl or html errors on you site.Google Analytics
This is by far the best website analytics application you can use, with lots of extra features like Goals and Real time data also the ability to be able to link in your Adsense account so you can see which pages earn you the most money is great.Keyword Density Tool
This tool comes in really handy when working on your on-page SEO, it will scan any page and return to you your most used keywords and the keyword density of each in a percentageOn Page Analysis
The on page analysis tool will scan any page and give you an instant On Page SEO report unlike many other which require you to add in an email and wait for it to arrive.Majestic SEO Tools
Majestic’s tools are very useful when comparing backlink data between your site and a competitors. Majestic has their own web index and it updates more then Yahoo Site Explorer, it also shows a lot more data.Google Toolbar
The Google Toolbar is great for checking a websites page rank!Alexa Toolbar
The Alexa Toolbar makes it easy to check a websites Alexa rank, it also allows people to see what a website used to look like.WordPress Plugins
All In One SEO
The all in one SEO plugin is really effective and can make your blog much more search engine friendly. It adds the ability to manually add in meta descriptions or to let the plugin auto generate them. It also make it easy to no index the tags and categories.Redirect Plugin
From time to time you need to setup a redirect and instead of using the WordPress’s basic redirect tool which only sets it up as a 302 redirect, you should be using the Redirect Plugin which allows you to setup 301 redirects easilyWP Super Cache
Site speed is important for your users, it also plays a small part in your search engine rankings, this plugin will most definitely increase your site speed.Free Downloadable Applications
SEO PowerSuite
Link Assistant AKA SEO PowerSuite provide a great set of tools which include and Rank checker, link assistant and a WebSite Auditor. They offer a free and paid version.Xenu’s Link Sleuth
Link Sleuth is a great tool for checking broken links, 404 pages and crawl errors.I will add to this list as I find more useful free tools. If this page has been useful to you please do Tweet + Like it!