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what is ilspy fr?

icsharpcode/ilspy — explained in plain English

Analysis updated 2026-06-21

25,093C#Audience · developerComplexity · 2/5LicenseSetup · easy

tl;dr

ILSpy is a free tool that lets you read the source code of any compiled .NET program, even when you don't have the original, it reconstructs readable C# from binary files.

vibe map

mindmap
  root((ILSpy))
    What it does
      Decompile binaries
      Browse metadata
      Export projects
    Tech stack
      C#
      .NET 10
    Use cases
      Debug dependencies
      Security audit
      Source recovery
    Audience
      .NET developers
      Security auditors

Code map

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filefunction / class

what do people make with this?

VIBE 1

Inspect how a third-party .NET library works internally when you don't have its source code.

VIBE 2

Debug an issue in a dependency by decompiling it and reading the reconstructed C# code.

VIBE 3

Audit compiled .NET software for security vulnerabilities or compliance checks.

VIBE 4

Recover source code from a compiled .NET program when the original has been lost.

what's the stack?

C#.NET.NET 10

how it stacks up fr

icsharpcode/ilspymxgmn/wavefunctioncollapsebeyonddimension/steamtools
Stars25,09325,02525,359
LanguageC#C#C#
Setup difficultyeasymoderatemoderate
Complexity2/53/53/5
Audiencedeveloperdevelopervibe coder

Figures from each repo's GitHub metadata at analysis time.

how do i run it?

Difficulty · easy time til it works · 5min
Open-source and free to use for any purpose including commercial projects.

in plain english

ILSpy is a free, open-source tool that lets you look inside compiled .NET programs, software built with C# or other .NET languages, even when you don't have the original source code. Compiled programs are normally stored as binary files (called assemblies) that computers can run but humans can't easily read. ILSpy reverses that process (called decompilation) and reconstructs readable C# code from those binary files. This is useful for understanding how a library works, debugging a dependency, or inspecting a program when the source has been lost. The tool works by reading .NET assembly files, parsing the low-level instructions (called Intermediate Language, or IL), and converting them back into human-readable C# code. It also supports browsing assembly metadata (information embedded in the file like type definitions and method signatures), navigating between types and methods with hyperlinks, and exporting entire projects worth of decompiled code. It handles modern .NET formats including ReadyToRun binaries, which are pre-compiled for faster startup. You would use ILSpy when you need to understand what a third-party .NET library does internally, when you want to debug an issue in a dependency you don't have source for, or when you are auditing software for security or compliance. It runs cross-platform on Windows, Mac, and Linux, and integrates with Visual Studio and Visual Studio Code as an extension. The tech stack is C# targeting .NET 10.

prompts (copy fr)

prompt 1
I have a .NET DLL file but no source code, how do I use ILSpy to decompile it and browse the C# code?
prompt 2
Show me how to install the ILSpy extension in Visual Studio Code and use it to inspect a NuGet package's internals.
prompt 3
Using ILSpy, how can I export a full decompiled project from a .NET assembly so I can open it in Visual Studio?
prompt 4
How do I use ILSpy to find a specific method inside a compiled .NET library and understand what it does?

Frequently asked questions

what is ilspy fr?

ILSpy is a free tool that lets you read the source code of any compiled .NET program, even when you don't have the original, it reconstructs readable C# from binary files.

What language is ilspy written in?

Mainly C#. The stack also includes C#, .NET, .NET 10.

What license does ilspy use?

Open-source and free to use for any purpose including commercial projects.

How hard is ilspy to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is ilspy for?

Mainly developer.

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