Whether you're developing a new site, or enhancing an existing site, these are some of the best free SEO tools I've found.
- Google Analytics - If you're exposing your site externally, this is a must have.
- Google Webmaster Tools - This is another required tool if site is external.
- Bing Webmaster Tools - Microsoft's version of Google webmaster tools. It's optional, but recommended.
- Google Adwords Keyword Tool - Starting point for keyword researc
- Google Trends - great for checking query volumes
- Ubersuggest - Keyword research ideas.
- SEOBook - Has booth free and paid tools
- SEO Site Tools - Chrome plugin
- MozBar - SEO toolbar for chrome/firefox
- SEO Quake - SEO toolbar for Chrome. Obtains information about any site. Helps with keyword competition determination.
- Builtwith - Shows behind the scenes info for competitor websites
- Xenu - Desktop app for finding broken links
- Browseo - View your site how a search engine does
- Internet Marketing Ninjas On-Page Optimization Analysis - on-page analysis tool to check internal/external links
- XML Sitemap Generator - create your XML sitemap
- Rich Snippets Testing Tool - See how Google views your structured data markup.
- Duplicate Content Checker
- Majestic SEO - Link explorer tool.
- Open Site Explorer - Link explorer tool.
- Ahrefs - Link analysis tool. Track keyword rankings for your site.
- Screaming Frog SEO Spider Tool - Desktop app that spiders websites links, images, css, scrips from an SEO perspective.
- Alltop - Good for finding topics for potential outreach opportunities (link building).
- Visual.ly - Get proven infographics for your topic.