Free of charge Resources of available Webmaster Tools and Accessible Online Tests on the Internet

Browser Check Go to Browser Sniffers. An annotated index. This is where you'll find free Web-based browser sniffers that reveal your browser's capablities (browser version, name, javascript/java capabilities, object/method support).

JIM HTML Toolkit. View URL's at different screen sizes. Just select the URL of the page you want to verify, select the want to employ (for normal browser windows, check them all) and hit the Open Window button. Normally you will want to check 640 x 480, 800 x 600, 1024 x 768, and 1280 x 1024.

ZDNet, Web Tools: Browser Check The Browser Check robot help you identify and fix compatibility problems. Excellent!