- IE Platform Status - which features (HTML, CSS, JS) are built in IE, are yet planned or developed. For each feature the support in Chrome, Firefox and Safari is noted, too.
- Chromium Dashboard - status of implementation of features (HTML, CSS, JS) in Blink (Chrome and Opera). Implementation status in IE, Firefox and Safari is noted, too.
- Introduction to Filters and Transitions - Dive into the early ideas of CSS3, as they still were IE-specific filters. They can help you mimic CSS3 for oldIE
- Webkit CSS properties - all webkit-specific CSS-properties with explanatory pages
- Webkit Extensions - all webkit-specific CSS-properties with explanatory pages
- Mozilla CSS Extensions - all Mozilla-specific CSS-properties with explanations
- CSS Compatibility and Internet Explorer - Which properties does IE support since which version? First-hand informations from Microsoft
- webbrowsercompatibility.com - Compatibility tables showing support for front-end technologies in web browsers
- Browserhacks.com - extensive list of hacks and filters to separate browsers regarding version numbers
- smaller List of CSS-Hacks
- virtual IE-machines - free virtual machines provided by Microsoft, even for OSX and Linux
- The Android Browser - presentation about the very disparate Webkit-/Blink-platform on mobile devices
- box-shadow versus box-shadow - a comparison of box-shadows in different browsers