THREE ways to check your WEB SITE’S compatibility with different browsers.
Good Web designers know that every browser version shows every web page a little
differently. Perfect Web designers have every browser ever created. For the rest of us
mere mortals, you can find online services that let you load your pages the way different
browsers see them. Others will also tell you what's wrong. See the differences ANYBrowser.com actually displays your Web page based on the different specifications of HTML. It doesn't display them by browser brand. It still gives you a look at how those with older browsers see your page.
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Web Site Garage doesn't actually display the page but tells you exactly what's wrong with your code as it relates to different browsers, including recommendations to change your code. The free version only lets you do one page at a time.
Net Mechanic gives you a comprehensive chart showing what tags cause problems in what browsers. It's a little hard to read and the recommendations to fix problems are a little vague.