Running multiple versions of IE simultaneously

Webmasters and designers of the web rejoice: a way has been found to run multiple versions of Microsoft Internet Explorer on one windows partition simultaneously. No longer do you need multiple machines, partitions, or vmware. Just grab the relevant dlls and files and add a blank text file named IEXPLORE.exe.local to the directory.

The technique was discovered by Joe Maddalone when he examined the files Microsoft included in the developer’s edition of IE6 that was released in response to the Eolas lawsuit. He was surprised by the limited number of files and the fact that it ran side by side with his existing version if IE. Adapting the technique, he was able to run IE5.01, IE5.5 SP2, and IE6 all at the same time. There’s a few problems, such as using the favorites menu crashing the browser and that the about menu reports the wrong version, but I’ve used this to have both IE5.5 and IE6 running on Windows XP. I also used IE5.0 and IE5.5 on Windows NT 4. I noticed a few oddities when loading the same test page in multiple browsers. They apparently share the cache, so they don’t always show the appropriate page.

This is great news [via LCKY]! I look forward to seeing refinements of this technique. Personally I’d like to be able to use this to run not only different versions of IE, but IE with different versions of the Microsoft and Sun Java VMs. I don’t know if that will be possible. For those that need to test CSS and DHTML, this will be very helpful.