The de facto .NET decompiler has been Reflector for what seems like forever.
Reflector was originally developed by Lutz Roeder, and made freely available to the community.
It was acquired by Red Gate Software in August 2008, who promised to maintain it as a free product.
They reneged on this promise in February 2011, stating that Reflector would become a commercial product.
This created a community backlash, culminating in creation and/or promotion of several free rival products through open source or offered by other vendors.
Red Gate backpedalled in April 2011 by saying that the final 6.8 version of Reflector would continue to be free, while future releases of Reflector (moving forward with version 7.x) would be paid for.
List of .NET Decompilers
|ILSpy||SharpDevelop||Open Source||C# 4 except for expression trees, dynamic, fixed fields||ILSpy development was started directly as a result of Red Gate’s announcement that Reflector would be paid for.|
|CodeReflect||DevExtras||Free (Commercially supported)||MSIL, C#, VB.NET|
|JustDecompile||Telerik||Free (Commerically supported)|
|dotPeek||JetBrains||Free (Commercially supported)||C#|
|Reflector 6.8||Red Gate||Free||MSIL, C#, VB.NET, more through plugins||Any future versions (7.x) are paid for. You need to be an existing Reflector user, and allow your Reflector to update to version 6.8.|