Accessibility
Functional Accessibility Evaluator
Use this tool to evaluate the functional accessibility of your web site.
Wave is my favorite Accessibility service – it shows you the mistakes and it is quite productive.
Cross Browser Testing
A great service for testing your site on all browsers on most operating systems.
This is a tool that incorporates all version of IE in one desktop application..
Search Engine Optimization
An analysis tool best used to see ranking keywords for your site.
Another analysis tool to show more issues regarding your site.
A good tool to see how your title tag, meta description, and rich snippets will look in Google’s search results.
Validating
The CSS Validator – validates CSS stylesheets or documents using CSS stylesheets.
This HTML Validator – checks the markup validity of Web documents in HTML, XHTML, SMIL, MathML, etc.
The Link Checker analyzes anchors (hyperlinks) in a HTML/XHTML document. Useful to find broken links.
This is the W3C Feed Validation Service, a free service that checks the syntax of Atom or RSS feeds
Website Performance Testing
Analyzing your website speed and breaking down the way elements are loaded.
The authority tool in optimizing your website and gaining additional speed.
A simple yet very useful service that generates a report related to your website performance.