Google Webmaster Tools
- Submit Your Website to Google
- Google Webmaster Checklist
- Official SEO Starter Guide (By Google)
- Google Keyword Tool and Google Search Based Keyword Tool
Yahoo! Site Explorer
Bing Webmaster Toolbox
- Submit Your Website to Bing
- Bing Webmaster Tools
- Bing SEO Basics Guide
- Bing Developer Tools
- Follow the Bing SEO Blog
Free SEO Software
- Google Website Optimizer
- Link Sleuth, Broken Link & Image Validation
- HTTPWatch Redirect Validation
- Free XML Sitemap Generator
- Website Grader – Site Audit Tool
- Darxx SEO Audit Tool
- Qualidator (Bad Ass Tool)
- Test Page Load Time
- Measure Your Inbound Links
- Check Traffic & Source Estimates