Accessibility
A2 solutions Visualisation Tool, Accessify.com, AIS - Web Accessibility Toolbar, Anybrowser - screen size testing, Bobby WorldWide, Color Vision - by Cal Henderson, Colorblind Web Site Filter, Cynthia Says Portal, Hermish, HiSoftware.Com Accessibility and Quality Tester
Alpha Squared Solutions Website Spell Checker
Free tool to check website spelling including meta tags, alt, title, longdesc and content. Languages include British English, American English, French, German, Spanish and Portuguese.
Backward Compatibility Viewer
Web page viewer for checking backward compatibility according to HTML version standards or specific features.
Squarefree Bookmarklets
Includes tools for viewing and testing CSS styles, viewing scripts and variables, and showing the structure of a document.