dnSpy

This software lets you use it without installing it making it possible to use it anywhere. The interface is easy to use. It has a wide range of tools. It gives you access to a debugger, hex editor, decompiler, and an assembly editor. When writing your own software or needing something to disassemble something, this is an editor that has it all and has been made to be easy to use.

Features:

• No set-up required it is very portable. No installation required
• An understandable interface - standard Windows menus
• .NET disassembler
• Reverse engineer .NET assembles
• Edit assemblies in C# or Visual Basic or IL, and edit all metadata

Whether you are writing your own software and needing to disassemble it to determine how it is working or if you are trying to see how another program functions, this program is what you need. Very user-friendly and everything a software developer could need in an assembly editor.

You don't have to install it on the computer which makes it very portable.

When needing to disassemble a program, this will give you all the various programs you will be needing in one simple package. The Window interface has the standard menu options that we are used to seeing in Window programs making it easy to understand how to interact with the software. It is very extensive with all of the different tools that are made available to you in one comprehensive program. It has many settings to do the work that you need when debugging, decompiling or needing a hex editor. The best part is that you can use it on any computer since you don't have to install it. It is ready to use. 

It's designed that you can do multiple debugs at the same time. You don't have to have the source code to be able to use the program. 

It makes your work efficient since it lets you easily reverse engineer assemblies.