← LeaderboardThe Skill Leaderboard

ilspy-decompile

Understand implementation details of .NET code by decompiling assemblies. Use when you want to see how a .NET API works internally, inspect NuGet package source, view framework implementation, or understand compiled .NET binaries.

Description awaits a fresh source check.

Published by Aaronontheweb ↗Aaronontheweb/dotnet-skills

Try your first task

ilspy-decompile

Start a fresh conversation. Replace the highlighted placeholders.

Use ilspy-decompile to decompile [assembly path and the API or type to inspect] to explain its implementation, including the relevant decompiled code and any caveats from the binary; proceed only if I am authorized to decompile it.

Required inputs

[assembly path and the API or type to inspect]

User-approved starter prompt based on a pinned source version; check current skill requirements before running. Task evidence ↗

SKILL.md

name: ilspy-decompiledescription: Understand implementation details of .NET code by decompiling assemblies. Use when you want to see how a .NET API works internally, inspect NuGet package source, view framework implementation, or understand compiled .NET binaries.allowed-tools: Bash(dnx:*)

.NET Assembly Decompilation with ILSpy

Use this skill to understand how .NET code works internally by decompiling compiled assemblies.

Prerequisites

.NET SDK installed
ILSpy command-line tool available via one of the following:
- dnx ilspycmd (if available in your SDK or runtime)
- dotnet tool install --global ilspycmd

Both forms are shown below. Use the one that works in your environment.

Note: ILSpyCmd options may vary slightly by version.
Always verify supported flags with ilspycmd -h.

Quick start

# Decompile an assembly to stdout
ilspycmd MyLibrary.dll
# or
dnx ilspycmd MyLibrary.dll

# Decompile to an output folder
ilspycmd -o output-folder MyLibrary.dll

Common .NET Assembly Locations

NuGet packages

~/.nuget/packages/<package-name>/<version>/lib/<tfm>/

.NET runtime libraries

dotnet --list-runtimes

.NET SDK reference assemblies

dotnet --list-sdks

Reference assemblies do not contain implementations.

Project build output

./bin/Debug/net8.0/<AssemblyName>.dll
./bin/Release/net8.0/publish/<AssemblyName>.dll

Core workflow

Identify what you want to understand
Locate the assembly
List types
Decompile the target

Commands

Basic decompilation

ilspycmd MyLibrary.dll
ilspycmd -o ./decompiled MyLibrary.dll
ilspycmd -p -o ./project MyLibrary.dll

Targeted decompilation

ilspycmd -t Namespace.ClassName MyLibrary.dll
ilspycmd -lv CSharp12_0 MyLibrary.dll

View IL code

ilspycmd -il MyLibrary.dll

Notes on modern .NET builds

ReadyToRun images may reduce readability
Trimmed or AOT builds may omit code
Prefer non-trimmed builds

Legal note

Decompiling assemblies may be subject to license restrictions.