1. Wordstream (http://www.wordstream.com/free-keyword-tools): This tool offers thousands of keyword ideas from a huge database of more than a trillion unique searches.
2. Keyword Eye Basic (http://www.keywordeye.com/) : This is type of keyword suggestion tool, that works particularly well for brainstorming sessions.
3. YouTube Keyword Tool (https://www.youtube.com/keyword_tool): It's for keyword research tool for all kinds of content, not just video.
4. Übersuggest (http://ubersuggest.org/) : It's use for developing long-tail phrases.
5. Anchor Text Over Optimization Tool (http://www.removeem.com/ratios.php) : To check Words or phrases that are potentially over-optimized are highlighted for manual review.
6. Convert Word Documents to Clean HTML (http://word2cleanhtml.com/) : Converter free tool for documents created in Microsoft Word, Writer, and other word processing software.
7. Copyscape (http://www.copyscape.com/) : To detect duplicate content and to verify that your content is original.
8. Xenu's Link Sleuth (http://download.cnet.com/Xenu-s-Link-Sleuth/3000-10248_4-10020826.html): PC based spidering software to check websites for broken links.
9. Robots.txt Generator (http://www.yellowpipe.com/yis/tools/robots.txt/) : Create robots.txt files
10. Robots.txt Checker (http://tool.motoricerca.info/robots-checker.phtml) : Analyze the syntax of a
robots.txt file
11. URI Valet (http://urivalet.com/) : To view total number of objects with external links along with
verifying server headers for each.
12. Title and Description Optimization Tool (http://seobin.org/) : Competitor intelligence tool for check title and description of a website.
13. Image SEO Tool (http://www.feedthebot.com/tools/alt/) : Enter the URL of a image and checks image name, alt attribute, and dimensions.
14. Schema Creator (http://schema-creator.org/) : Get started creating HTML with schema.org microdata.
15. Google Snippet Preview (http://www.snippetoptimizer.net/) : It helps to visualize and optimize what type of data to be displayed in search result for searchers.
16. Structured Data Testing Tool (http://www.google.com/webmasters/tools/richsnippets) : To use this tool for verifies Schema.org or any other structured data type markup.
17. XML Sitemap Generators (http://code.google.com/p/sitemap-generators/wiki/SitemapGenerators) : To create XML sitemap for website.
18. XML Sitemap Inspector (http://sitemapinspector.com/) : Validate your sitemap and repair their errors, and pings to all search engines.
19. Pingdom Website Speed Tool (http://tools.pingdom.com/fpt/) : This tool is use for test the load time of a page, analyzes it.
20. Fiddler (http://fiddler2.com/) : It is a web debugging tool which is use for logs all HTTP(S) traffic
between your computer and the Internet.
21. Microsoft Free SEO Toolkit (http://www.microsoft.com/web/seo) : Microsoft has created this tool for SEO audit, complete with detailed reports.
