Ilspy Decompile
- 433 installs
- 1.1k repo stars
- Updated July 3, 2026
- aaronontheweb/dotnet-skills
ilspy-decompile is a .NET debugging skill that decompiles assemblies with ILSpy to inspect third-party, framework, and legacy binary behavior when source code or documentation is unavailable.
About
ilspy-decompile is an aaronontheweb dotnet-skills skill that guides agents through .NET assembly decompilation using ILSpy command-line tooling. Prerequisites include the .NET SDK and ilspycmd via `dnx ilspycmd` or `dotnet tool install --global ilspycmd`. Developers use ilspy-decompile to reveal how NuGet packages, framework libraries, or legacy DLLs behave internally—tracing bugs, verifying API contracts, and mapping dependencies without original repositories. The skill fits integration debugging, security reviews of opaque binaries, and learning undocumented surface areas in compiled .NET code. Agents invoke it when questions arise about compiled behavior that docs and public source cannot answer, producing readable C#-like output from binaries.
- ILSpy decompilation workflow
- Third-party assembly inspection
- Legacy .NET troubleshooting
- Dependency behavior analysis
- Source-unavailable debugging
Ilspy Decompile by the numbers
- 433 all-time installs (skills.sh)
- Ranked #99 of 596 Debugging skills by installs in the Skillselion catalog
- Data as of Aug 3, 2026 (Skillselion catalog sync)
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| Installs | 433 |
|---|---|
| repo stars | ★ 1.1k |
| Last updated | July 3, 2026 |
| Repository | aaronontheweb/dotnet-skills ↗ |
How do you decompile .NET assemblies without source?
Decompile third-party or legacy .NET assemblies with ILSpy to inspect behavior, trace bugs, and understand dependencies when source code or documentation is unavailable.
Who is it for?
.NET developers debugging third-party NuGet packages, framework internals, or legacy binaries when source and docs are missing.
Skip if: Teams with full source access, non-.NET binaries, or workflows where decompilation violates license terms.
When should I use this skill?
A developer needs to see how a .NET API works internally, inspect a NuGet package, or understand compiled binary behavior.
What you get
Decompiled C#-like source views, dependency traces, and internal API behavior notes from ILSpy output.
- decompiled source output
- dependency insight
- internal API behavior notes
Files
.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.dllCommon .NET Assembly Locations
NuGet packages
~/.nuget/packages/<package-name>/<version>/lib/<tfm>/.NET runtime libraries
dotnet --list-runtimes.NET SDK reference assemblies
dotnet --list-sdksReference assemblies do not contain implementations.
Project build output
./bin/Debug/net8.0/<AssemblyName>.dll
./bin/Release/net8.0/publish/<AssemblyName>.dllCore workflow
1. Identify what you want to understand 2. Locate the assembly 3. List types 4. Decompile the target
Commands
Basic decompilation
ilspycmd MyLibrary.dll
ilspycmd -o ./decompiled MyLibrary.dll
ilspycmd -p -o ./project MyLibrary.dllTargeted decompilation
ilspycmd -t Namespace.ClassName MyLibrary.dll
ilspycmd -lv CSharp12_0 MyLibrary.dllView IL code
ilspycmd -il MyLibrary.dllNotes 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.
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How do you run ILSpy in ilspy-decompile?
ilspy-decompile supports `dnx ilspycmd` when available in the SDK runtime or `dotnet tool install --global ilspycmd`. The skill documents both entry points and requires the .NET SDK installed.
What should developers decompile with ilspy-decompile?
Developers should decompile third-party NuGet assemblies, .NET framework libraries, and legacy binaries when source or documentation is unavailable. The skill helps trace internal API behavior and dependencies.