Not all websites or blogs are compatible with all web browsers across different OS. This is where the need for such a service arises where we can test multiple websites across different browsers.
Adobe BrowserLab is a free online service that allows you to test your website design across multiple browsers. In short, it lets you know if your website is compatible with a certain browser. Just write a website address and hit Enter. You can choose the way you would like a website to be displayed, 1-up view, 2-up view, or Onion Skin View. Since I do a lot of comparing across different browsers, I personally prefer 2-up view.
Note: This service requires registration with Adobe. This is a serious downside but is worth it in my opinion. Since you can use the same username/password to log into other Adobe services too, such as Presentation.
It supports three web browsers IE, Firefox, and Safari across Windows and Mac. Linux and other OS are not supported at this moment.
Below is an example of how my website looks like in 2-up view. On the left is Safari 3.0 on Mac OS X, while on the right is Firefox 3.0 on Windows XP.
It can also be integrated with DreamWeaver CS4, in this way you won’t have to publish your website for testing. You will be able to do it from within the WYSIWYG HTML editor. Enjoy!