My colleague was fighting against a nasty bug, that only occures on one machine. Unfortunatly this machine was not a development machine (no VS installed) and we didn’t want to mess with VS remote debugging, because (AFAIK) his would need some additional setup but we were not allowed to install anything.
Soooo… he searched around and found this:
dnSpy - a .NET assembly editor, decompiler, and debugger
The title contains the major points. It is a decompiler, like IL Spy, but addionaly it has a super nice debugger and it looks like a small Visual Studio.
Some pictures how I just decompile Paint.NET and attach the debugger:
I think this is just awesome and it helped my colleague alot.
OSS & Free
The complete project is hosted on GitHub and is “Open Source (GPLv3) and Free Forever”
Checkout the GitHub project page - it contains a lot more information. The tool itself was just 18mb zipped and can be run everywhere.
Its a decompiler!
And just to make sure you keep this in mind: The debugging works with every .NET application (at least in theory), because it decompiles the .NET IL language to C#. It is not a 1:1 debugger, but maybe it can help you.