How do I install the Ilspy Decompile skill?

Run npx skillmds@latest add envoydev/ilspy-decompile in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Ilspy Decompile free to use?

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Who published Ilspy Decompile?

envoydev (@envoydev) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Ilspy Decompile by envoydev — Agent Skill

Name: Ilspy Decompile
Author: envoydev

Ilspy Decompile

Decompile a compiled .NET assembly to read its real implementation - see how a framework or NuGet API actually works, view source you do not ship, or confirm behavior before a framework upgrade. Uses ilspycmd (via dnx or a pinned global tool). Load when you need ground truth from a .dll instead of guessing at an API, not for source you already have (that is serena / the LSP). Companions: `dotnet-migrate` (upgrade investigation), `csharp`.

envoydev da8fb57 2.2 KB Updated Sep 17, 2026

File contents

ilspy-decompile

Decompile a compiled assembly when you need the real implementation - a framework internal, a NuGet package you have no source for, or the exact behavior of a method before you upgrade across it. For source you already have, navigate with serena / the LSP instead; this is only for compiled .dll you cannot open otherwise.

Tool

ilspycmd, via either form (pick whichever the environment has):

dnx ilspycmd -h                       # needs the .NET 10 SDK
dotnet tool install --global ilspycmd # or pin per-repo in .config/dotnet-tools.json

Flags vary by version - confirm with ilspycmd -h.

Locate the assembly

NuGet package: ~/.nuget/packages/<package-name>/<version>/lib/<tfm>/
Build output: ./bin/Debug/net8.0/<AssemblyName>.dll (or Release/.../publish/)
Runtime libraries: the shared-framework folder under the SDK (dotnet --list-runtimes shows the paths). Reference assemblies hold no implementation - decompile the runtime .dll, not the ref.

Commands

ilspycmd MyLibrary.dll                       # whole assembly to stdout
ilspycmd -o ./decompiled MyLibrary.dll       # to a folder
ilspycmd -p -o ./project MyLibrary.dll       # reconstruct a .csproj
ilspycmd -t Namespace.ClassName MyLibrary.dll # one type only (fastest)
ilspycmd -il MyLibrary.dll                   # raw IL

Workflow: identify what you want to understand, locate the assembly, decompile the one type (-t) rather than the whole thing.

Modern-build caveats

ReadyToRun images, trimmed builds, and NativeAOT all reduce or omit decompilable code - prefer a non-trimmed Debug/Release build when you have the choice. Decompiling third-party code may be license-restricted; use it to understand, not to redistribute.

---name: ilspy-decompiledescription: Decompile a compiled .NET assembly to read its real implementation - see how a framework or NuGet API actually works, view source you do not ship, or confirm behavior before a framework upgrade. Uses ilspycmd (via dnx or a pinned global tool). Load when you need ground truth from a .dll instead of guessing at an API, not for source you already have (that is serena / the LSP). Companions: `dotnet-migrate` (upgrade investigation), `csharp`.---# ilspy-decompileDecompile a compiled assembly when you need the real implementation - a framework internal, a NuGet package you have no source for, or the exact behavior of a method before you upgrade across it. For source you already have, navigate with serena / the LSP instead; this is only for compiled `.dll` you cannot open otherwise.## Tool`ilspycmd`, via either form (pick whichever the environment has):```bashdnx ilspycmd -h # needs the .NET 10 SDKdotnet tool install --global ilspycmd # or pin per-repo in .config/dotnet-tools.json```Flags vary by version - confirm with `ilspycmd -h`.## Locate the assembly- NuGet package: `~/.nuget/packages/<package-name>/<version>/lib/<tfm>/`- Build output: `./bin/Debug/net8.0/<AssemblyName>.dll` (or `Release/.../publish/`)- Runtime libraries: the shared-framework folder under the SDK (`dotnet --list-runtimes` shows the paths). Reference assemblies hold no implementation - decompile the runtime `.dll`, not the ref.## Commands```bashilspycmd MyLibrary.dll # whole assembly to stdoutilspycmd -o ./decompiled MyLibrary.dll # to a folderilspycmd -p -o ./project MyLibrary.dll # reconstruct a .csprojilspycmd -t Namespace.ClassName MyLibrary.dll # one type only (fastest)ilspycmd -il MyLibrary.dll # raw IL```Workflow: identify what you want to understand, locate the assembly, decompile the one type (`-t`) rather than the whole thing.## Modern-build caveatsReadyToRun images, trimmed builds, and NativeAOT all reduce or omit decompilable code - prefer a non-trimmed Debug/Release build when you have the choice. Decompiling third-party code may be license-restricted; use it to understand, not to redistribute.

Frequently asked questions