Firstly IE8, IE9, IE10 and IE11 all have developer tools (just press F12 whilst in Internet Explorer) these allow you to change your document and browser mode to go back to older rendering engines such as IE6. With IE11 comes a new set of greatly improved tools, but there is a good introduction talk over at Build.
This tool detects common coding practices that may cause compatibility problems or prevent your users from getting the best possible experience on a webpage. Whenever possible we suggest a fix or enhancement with web standards like HTML5 & CSS3 (or a graceful fallback). Enter your domain name only in Modern.ie scanner. The scanner then uses a node.js services (which is available on GitHub) to go fetch the website and interrogate it to locate common problems, it then provides a report which details what you may need to do to fix you website so that it works well in IE and also other stands based browsers.
No more choosing between Windows or Mac at startup, VMware Fusion lets you run Windows and Mac applications side-by-side directly from your existing Boot Camp partition. Run your favorite Windows applications alongside Mac applications without rebooting. Whether you would like to run Windows XP, Windows 7 or Windows 8.1 on a Mac, the VMware Fusion easy install feature will get you up and running in no time. With the ability to run Windows-only applications like Microsoft Project, Access and Internet Explorer, VMware Fusion turns your Mac into the ultimate computer for compatibility.
HOSTED VIRTUAL MACHINES (BROWSERSTACK)
Modern.ie provides a 3 month free trial for BrowserStack which allows you to test IE6-10 (and every other major browser like Chrome, Opera, Safari, Firefox as well as iOS and Android emulators) inside of your browser. There are also browser plugins available for Chrome and Firefox which make launching BrowserStack even easier.
With BrowserStack you can simply start up a new Virtual machine in the cloud running practically any OS and then test your website in that environment.
Please note that there are multiple applications like this. Choose the one that works best for you. I prefer VMWare Fusion, though admittedly, I don’t have a huge amount of experience with the others.