Largest Collection of SEO Tools

• Swiss Army Knives for SEO
• These SEO tools check multiple SEO metrics in one step: Google PageRank, Alexa Rank, Compete Rank, Quantcast Rank, Google Backlinks, Yahoo Backlinks, MSN Live Search Backlinks, Technorati Links, del.icio.us Bookmarks, Rojo links, Bloglines subscribers.
• SEOmoz Page Strength SEO Tool
• popuri.us
• Rank Alert: Site Rank Report
• webconfs: Domain Stats Tool
• SEOcompany.ca: Website Analysis Tool
• socialmeter
• Seitwert (German)

• Firefox SEO Extensions

• It should come as no surprise that you need Firefox to use the following tools. Similar to the Swiss army knives above many of the Firefox extensions listed perform various SEO related tasks and allow you to check: Google PageRank, Google Category, Alexa Rank, Compete Rank, Alexa related links and backward links from Google, Yahoo!, Alexa and MSN.
• SearchStatus
• SeoQuake
• RankQuest SEO Toolbar
• SEOpen
• SEO Tools
• KGen
• SEO Book: SEO for Firefox

• Search Engine Tools

• Tools available from major search engines.
• Yahoo! Site Explorer
• Google Sitemaps
• Google Trends

• Keyword Research and Analysis

• These tools are useful for keyword research, keyword analysis, checking keyword frequency, and getting keyword suggestions.
• SEO King: Overture Keyword tool
• SEO Book Keyword Suggestion Tool
• Google AdWords: Keyword Tool
• Rank Alert: Keyword Popularity Checker
• We Build Pages: Search Combination Tool
• webconfs: Website Keyword Suggestions
• SEO Book: Text Rank Checking Tool for Google
• Overture: Keyword Selector Tool
• We Build Pages: Cool Domain Age Checker
• Overture: Keyword Selector Tool
• Overture: Suchbegriffe finden (German)
• MetaGer-Web-Assoziator (German)
• Keyword Datenbank mir KEI-Berechnung (German)
• Keyword Datenbank (German)
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• Keyword Ranking Tools

• Tools for checking the search engine rankings for specified keywords on your site and/or top ranking sites (keyword competition).
• We Build Pages: Top Ten Analysis SEO Tool!
• SEOcompany.ca: Keyword Top 10 Site Info
• We Build Pages: Top Competitor Tool
• We Build Pages: Deep Link Ratio Tool
• SEO Book: Google Advanced Keyword Rank Checker
• Suchmaschinen Ranking (German)

• Keyword Density Tools

• Tools for analyzing the keyword density of web pages.
• We Build Pages: Keyword Density Analysis Tool
• SEO Book: Keyword Density Analyzer Tool
• iWebtool:Keyword Density Checker
• webconfs: Keyword Density Checker - Keyword Cloud

• Google PageRank Tools

• Tools for checking, monitoring, and predicting Google PageRank.
• iWebtool: Visual PageRank
• Smart PageRank
• iWebtool: Multi-Rank Checker
• Rank Alert: Data Center Watch
• iWebtool: Google PageRank Prediction

• Backlink Checkers

• Tools for checking backlinks and anchor texts found in various search engines and suggestions for linkbuilding.
• webconfs: Backlink Builder
• We Build Pages: Common Backlinks Tool!
• Free Backlink Checker
• We Build Pages: Strongest Subpages Tool
• iWebtool: Backlink Checker
• We Build Pages: C Class Backlink Analyzer
• Rank Alert: Backlink Watch

• Link Tools

• Tools for extracting links and searching websites for broken links.
• iWebtool: Link Extractor
• Rank Alert: Link Validator Check Broken Links
• Xenu's Link Sleuth (Web Client)

• Web Statistics and Tracking

• Tools for analyzing website traffic and visitor tracking.
• Google Analytics
• Webalizer (Web Server)
• AWStats (Web Server)
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• Crawling Test and Speed Check Tools

• Tools for checking out how search engine crawlers (spiders) "view" web pages and how fast they are downloaded with different Internet connection bandwidths.
• SEO Book:Spider Test
• iWebtool: Spider View
• webconfs: Search Engine Spider Simulator
• Free Website Performance Tool and Web Page Speed Analysis
• iWebtool: Website Speed Test

• Meta Tag Tools

• Tools for generating, optimizing, and extracting meta tags.
• SEO King: Meta tag optimization
• SEO Book Meta Medic
• iWebtool: Meta-tags Generator
• iWebtool: Meta-tags Extractor

• Domain Tools

• Tools for retrieving data about domains, such as age and ip address, tools for finding expired domains, and domain name suggestion tools.
• Stuckdomains: Free Expired Domains Search
• Nameboy: Domain Name Generator
• AjaxDomainSearch
• webconfs: Keyword-Rich Domain Suggestion Tool
• iWebtool: Reverse IP/Look-up
• iWebtool: Ping Test
• webconfs: Domain Age Tool
• Netcraft Site Report

• HTTP header viewer

• Tools for viewing the HTTP header send to clients after requesting web pages.
• SEO King: HTTP header viewer
• iWebtool: HTTP Headers

• Misc Tools

• Tools that don't fit into any of the above categories.
• webconfs: Search Engine Friendly Redirect Checker
• webconfs: URL Rewriting Tool
• iWebtool: HTML Optimizer
• iWebtool: Alexa Traffic Rank
• iWebtool: Search Listings Preview
• iWebtool: Server Status
• iWebtool: Google Banned Checker
• Text Link Ads: Ad Link Value Calculator

• Adsense Calculator
  Google AdSense affiliates can use this calculator to gain a better understanding of what affects their earnings by experimenting with values.
   

• AdSense Preview
  This preview utility will give you a sense of which ads would be placed on a given page.
  　
• Advanced Meta Tag Generator
  This tool helps you to add meta tags to your site.
  　
• Alexa Rank Comparison Tool
  The Alexa Traffic History Graph allows you to create a traffic history graph for any site.
  　
• Check Server Headers
  Check your server to make sure the proper HTTP Status Codes (200, 301, 302, 304, 307, 404, 410) are being returned in the server headers.
  　
• Class C Checker
  This Class C Checker tool allows you to find out whether some sites are hosted on the same Class C IP Range.
  　
• Code to Text Ratio
  This tool will help you discover the percentage of text in a web page (as compared to the combined text and code).
  　
• CPM Calculator
  This calculator measures the ROI (return on investment) of the CPM (cost per thousand) impressions advertising model.
  　
• Domain Age Check
  Use this tool to find the age of a domain.
  　
• Domain Typo Generator
  Enter a domain name into the box, and this tool will generate a list of suggestions of likely human misspellings and typos for the given domain.
  　
• Future PageRank
  This tool will query Google's various data centers to check for any changes in PageRank values for a given URL.
  　
• Google Dance
  This tool will query Google's three main web servers, showing the different statuses during updates. Watch Google Dance.
  　
• Google Keyword Suggestions
  The keyword suggestion tool for Google will help you choose relevant and popular terms related to your selected key term.
  　
• Google Search for Multiple Datacenter
  This tool searches your keyword/phrase in different Google data centers.
  　
• Google Suggest Scraper
  Shows frequently search for phrases starting with the words and letters in your query.
  　
• Google vs Yahoo
  This tool will run a search query in Google and Yahoo search engines and then graphically compare the results.
  　
• Indexed Pages
  This tool will return the total link count for each URL from major search engines (Google, Yahoo, MSN, Alta Vista, and AlltheWeb).
  　
• Keyword Cloud
  This tool provides a visual representation of keywords used on a website.
  　
• Keyword Density
  This tool will analyze your chosen URL, and return a table of keyword density values for one-, two-, or three-word key terms.
  　
• Keyword Difficulty Check
  Use the Keyword Difficulty Check Tool to see how difficult it would be to rank for specific keywords or keyword phrases.
  　
• Keyword Optimizer
  Enter a list of keywords and this tool will remove any duplicate entries and re-order the list alphabetically.
  　
• Keyword Position Check for Multiple Datacenter
  This tool will help you to find the position of your site in Google for a specific keyword/phrase.
  　
• Keyword Typo Generator
  Enter a keyword or key term into the box above and this tool will generate a list of suggestions for likely human misspellings and typos.
  　
• Link Popularity
  Enter a valid URL, and this tool will query all the major search engines (Google, Yahoo, MSN, and Teoma) and then return that URL's total link count for each one.
  
  Link Price Calculator
  This tool can help you determine the approximate amount you should be paying per month for a text link.
  　
• Meta Analyzer
  This tool will analyze a website's meta tags. Analyzing a competitor's keyword and description meta values is a good way to find ideas for key terms and more effective copy for your site.
  　
• Meta Tag Generator
  If you're new to web development and search engine optimization, you may find this tool useful to ensure that your meta tags are correctly formed..
  　
• Multiple Datacenter Link Popularity Check
  This tool will give a back link count for a URL from multiple Google data centers.
  
  　
• Overture Keyword Suggestions
  Simply enter a key term and this tool will query information from the Overture database of searched terms.
  
  Page Comparison
  Compares the page titles, meta information, and common phrases occurring on different pages.
  
  Page Size
  This tool will help you to determine HTML web page size.
  
  PageRank Lookup
  This tool streamlines the process of checking PageRank for your sites. Enter a list of URLs and it will return the PageRank value for each one.
  
  PageRank Search
  Enter your Google search here, and our tool will search Google and display the PageRank next to each resulting answer.
  
  Robots.txt Generator
  Use this tool to generate a simple robots.txt file for your website, which allows you to hide files or directories that you don?ft wish to be spidered.
  
  ROI Calculator
  This calculator measures the ROI (return on investment) of a CPC (cost per click) campaign.
  
  Search Engine Comparison
  This tool allows you to perform your own comparisons, and displays the results visually, making it easy to see both the rankings and comparative positions of pages in search engine results.
  
  Search Engine Keyword Position
  This tool checks the search engine result pages of Google, Yahoo, and MSN to see what position your site holds for a particular keyword phrase.
  
  Site Link Analyzer
  This tool will analyze a given web page and return a table of data containing columns of outbound links and their associated anchor text.
  
  Spider Simulator
  This tool simulates a search engine spider by displaying the contents of a web page in exactly the way the spider would see it.
  
  URL Redirect Check
  This tool checks for valid HTTP 301 headers.
  
  URL Rewriting
  This tool converts dynamic URLs to static URLs. You will need to create an .htaccess file to use this tool.
• Google AdSense Charts
  Generate all sorts of nifty charts with your AdSense CSV data export (requires a Google AdSense account of course).
• Google AdSense Sandbox
  This tool will show you what Google AdSense ads will be displayed for any webpage on the Internet.
• Back Link Tracking Tool
  Track backlink fluctuations to your web pages historically.
• Coop Ad Network
  Free network of site owners to share advertising space.
• Diff Comparison
  Tool to show you the difference between two pieces of text.
• DNS Zone Transfer
  Handy little utility to quickly pull your DNS zone files from your name servers.
• FileMaker Pro Web Digger
  This utility allows you to dig into your web-based FileMaker Pro databases to check their security.
• FileMaker Database Server Probe
  This utility allows you to check your FileMaker database server to see what platform it's running as well as what database files are being served.
• Keyword Ranking Monitor
  Track historical search engine result placement data for any keyword/URL combo you choose.
• Keyword Suggestion Tool
  Quickly see which phrases are searched upon the most (for determining the best phrases to target for your website).
• PageRank Toolbar For Mac
  A widget to show PageRank for the site you are on.
• Add Search Functionality To Your Website
  An easy way that you can add search functionality to any website.
• Free Web Counter
  Free tool that gives any website a free hit counter for their site.
• Website To Country
  Find the physical country that any website is in.
• Geo Visitors
  Show the physical location of the visitors to your website/blog.
• Yahoo! Web Rank Tool
  This tool will show you what any website's Yahoo! Web Rank is (without needing the Yahoo toolbar).
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