If you consider that search engine optimization (SEO) is a scientific discipline, then you’ll agree that obtaining empirical measurements using a comprehensive suite of tools is an absolute must. Every day should be filled with experimentation, data collection and more experimentation. Flying blind is not an option.

So, let’s not waste any time. There is a plethora of data to be mined and insights to be gleaned. Here I share with you some, but by no means all, of my favorite free (unless otherwise noted) SEO tools. Note that in order to minimize redundancy, I have excluded those tools which I had previously covered in my “Tools For Link Building” article (April 2006 issue).

For Keyword Research:

WordTracker.com – A paid tool. Data is based on the Metacrawler search engine.

KeywordDiscovery.com – A paid tool. Data is based on the number of search engines.

Overture Keyword Selector (inventory.overture.com) – Based on Yahoo! searches. Verb tenses, misspellings, singular and plural forms are all combined. Therefore, it’s more useful as a paidsearch tool than as an SEO tool.

Google Suggest (labs.google.com/suggest) – As you type, Google provides the top 10 most popular keywords that begin with the keyed-in letters, in order of popularity.

Google Trends (www.google.com/trends) – graphs historical trends of various Google searches.

Google AdWords Keyword tool (https:// adwords.google.com/select/KeywordToolExternal) – No hard numbers, unfortunately, but you can see historical trends in keyword popularity.

Googspy.com – See what keywords your competitors are buying.

SEOsleuth.com – Created out of the search data that AOL released earlier this year. View what keywords AOL users searched for and what sites they then went to, how much organic traffic each site got and how many clicks individual search results pages received.

Saturation Tools (to check indexation):

Yahoo! Site Explorer (siteexplorer.search.yahoo.com) – Check indexation on Yahoo!.

Netconcepts’ URL Checker (www.netconcepts.com/urlcheck)— Shows indexation levels across all major engines; also displays results of historical results from past checks.

Netconcepts’ Product Page Checker (www.netconcepts.com/productcheck) – Shows number of product or category pages (or any common string, by using the inurl: operator) indexed across all major engines; also displays past results from past checks.

For Link Analysis and PageRank:

Touchgraph.com – Shows visual map of who’s linking to you.

Live PageRank (livepr.raketforskning.com) – Reportedly obtains more up-to-date PageRank scores than what is displayed in the Google Toolbar.

Webmastereyes.com – Display a webpage overlaid with PageRank scores next to all links on the page.

Google Toolbar (toolbar.google.com) – For the built-in PageRank meter.

Google Directory (directory.google.com) – for the PageRank scores which are displayed on all category pages.

SEO for Firefox Extension (tools.seobook.com/firefox/seo-forfirefox. html) – PageRank, site age, saturation, back links, .edu and .gov links, Alexa rank, dmoz listings, etc.

SEOpen Firefox Extension (seopen.firefoxextension. com/index.php) – Back links, saturation, related pages, page size, keyword density, Wayback Machine, whois, Alexa data, etc.

SEOMoz PageRank Strength Tool (www.seomoz.org/tools/pagestrength. php) – Pulls in linking info from Yahoo! pages indexed in Google, domain age, .edu and .gov links, Alexa rank, PageRank, etc.

Netconcepts Link Checker (www.netconcepts.com/linkcheck) – Check inbound links across all major engines; also displays past results from past checks.

Reporting Tools:

Alexa Rank (www.alexa.com) – Traffic rank, site reach and historical traffic patterns.

Digitalpoint Keyword Rankings (www.digitalpoint.com/tools/keywords) – Check your site’s rankings by keyword.

Urltrends.com – Monitor PageRank, Alexa rank, back links, outbound links, etc.

Other Tools:

User Agent Switcher Firefox extension (useragent switcher.mozdev.org) – Pretend to be Googlebot when serving.

SwitchProxy Firefox extension (extensionroom.mozdev.org/moreinfo/ switchproxy) – Pretend to be a different IP address. Useful to see different paid search results.

The Scrutinizer (www.scrutinizethis.com) – One hundred seventy- one things you can do to your URL.

CopyScape (www.copyscape.com) – Website plagiarism search.

Poodle Predictor (gritechnologies.com/tools/spider.go)—See what your page will look like to spiders.

Xenu Link Sleuth (snafu.de/tilman/xenulink.html) – Broken link checker