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dnSpy is a debugger and .NET assembly editor. You can use it to edit and debug assemblies even if you don't have any source code available. Main features:

Debug .NET and Unity assemblies
Edit .NET and Unity assemblies
Light and dark themes

See below for more features

Binaries

https://github.com/0xd4d/dnSpy/actions

Building

git clone --recursive https://github.com/0xd4d/dnSpy.git
cd dnSpy
# or dotnet build
./build.ps1 -NoMsbuild

To debug Unity games, you need this repo too: https://github.com/dnSpy/dnSpy-Unity-mono (or get the binaries from https://github.com/0xd4d/dnSpy/releases/unity)

Debugger

Debug .NET Framework, .NET Core and Unity game assemblies, no source code required
Set breakpoints and step into any assembly
Locals, watch, autos windows
Variables windows support saving variables (eg. decrypted byte arrays) to disk or view them in the hex editor (memory window)
Object IDs
Multiple processes can be debugged at the same time
Break on module load
Tracepoints and conditional breakpoints
Export/import breakpoints and tracepoints
Call stack, threads, modules, processes windows
Break on thrown exceptions (1st chance)
Variables windows support evaluating C# / Visual Basic expressions
Dynamic modules can be debugged (but not dynamic methods due to CLR limitations)
Output window logs various debugging events, and it shows timestamps by default :)
Assemblies that decrypt themselves at runtime can be debugged, dnSpy will use the in-memory image. You can also force dnSpy to always use in-memory images instead of disk files.
Public API, you can write an extension or use the C# Interactive window to control the debugger

Assembly Editor

All metadata can be edited
Edit methods and classes in C# or Visual Basic with IntelliSense, no source code required
Add new methods, classes or members in C# or Visual Basic
IL editor for low-level IL method body editing
Low-level metadata tables can be edited. This uses the hex editor internally.

Hex Editor

Click on an address in the decompiled code to go to its IL code in the hex editor
The reverse of the above, press F12 in an IL body in the hex editor to go to the decompiled code or other high-level representation of the bits. It's great to find out which statement a patch modified.
Highlights .NET metadata structures and PE structures
Tooltips show more info about the selected .NET metadata / PE field
Go to position, file, RVA
Go to .NET metadata token, method body, #Blob / #Strings / #US heap offset or #GUID heap index
Follow references (Ctrl+F12)

Other

BAML decompiler
Blue, light and dark themes (and a dark high contrast theme)
Bookmarks
C# Interactive window can be used to script dnSpy
Search assemblies for classes, methods, strings, etc
Analyze class and method usage, find callers, etc
Multiple tabs and tab groups
References are highlighted, use Tab / Shift+Tab to move to the next reference
Go to the entry point and module initializer commands
Go to metadata token or metadata row commands
Code tooltips (C# and Visual Basic)
Export to project

List of other open source libraries used by dnSpy

ILSpy decompiler engine (C# and Visual Basic decompilers)
Roslyn (C# and Visual Basic compilers)
dnlib (.NET metadata reader/writer which can also read obfuscated assemblies)
VS MEF (Faster MEF equals faster startup)
ClrMD (Access to lower level debugging info not provided by the CorDebug API)
Iced (x86/x64 disassembler)

Translating dnSpy

Click here if you want to help with translating dnSpy to your native language.

Wiki

See the Wiki for build instructions and other documentation.

License

dnSpy is licensed under GPLv3.

Reg1350/dnSpy