I have a computer that does not run Windows.
I tried using IETester in a VirtualBox VM, but it crashes terribly often, making it extremely difficult to work with.
Is there any other way to test my site in IE8+, with debugging tools, preferably free (assuming I have a Windows license)?
I would recommend you to use Virtual Machine (VM), Windows Virtual PC & Browserstack | Modern.IE which is available for OSX, Linux or Windows.
As far as the instruction goes,
Download the EXE and all RAR files for the VM (smaller VMs may not have files with RAR extension). In each set below that contains a split archive, a provided text file (.txt) contains URLs to all files in the set, and the contents of this can be used directly with most download managers. For example, see http://www.freedownloadmanager.org/download.htm.
After the download of all files for a set is complete, run the EXE and choose location to extract VM.
Alternative Extraction Option
Regardless of the host platform that you are using, if you have problems using the self extracting archive, you can always install a program that can extract RAR files and use that to extract the VM.
Quoting from modern.IE
You want a tool / service which is free, but if you can spend some, try using BrowserStack where you can check your web pages in tons of browsers without installing them on your local machine.
Some of it's features:
It's not quite as useful as emulating the browser, but there are a few services that will provide you with a screenshot of your page. This won't be helpful if you need to test something like JavaScript functionality, but if you need to see how something renders then it's nice to use in a pinch.
netrenderer supports IE5.5 - IE11:
Browsershots currently only supports IE8, but there are lots of options for other browsers and operating systems.
