In computing, a decompiler is a computer program that takes an executable file as input, and attempts to create a high level, compilable source code file that does the same thing. A common type of decompiler is a Java decompiler, which takes a Java class file and converts it into Java source code.
There is not much information available on decompiling C# exe files. However, there are a few decompilers that claim to be able to do this, such as ILSpy and JustDecompile. It is unclear how well these decompilers work, or if they work at all.
In conclusion, it is possible to decompile a C# EXE file using a variety of different tools and services. However, it is important to note that this process is not always successful, and that the results may not be accurate.