Microsoft.Windows.CsWin32 0.1.691-beta The ID prefix of this package has been reserved for one of the owners of this package by Prefix Reserved

.NET Standard 1.0 .NET Framework 2.0
This is a prerelease version of Microsoft.Windows.CsWin32.
There is a newer prerelease version of this package available.
See the version list below for details.
Install-Package Microsoft.Windows.CsWin32 -Version 0.1.691-beta
dotnet add package Microsoft.Windows.CsWin32 --version 0.1.691-beta
<PackageReference Include="Microsoft.Windows.CsWin32" Version="0.1.691-beta">
  <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Microsoft.Windows.CsWin32 --version 0.1.691-beta
The NuGet Team does not provide support for this client. Please contact its maintainers for support.
#r "nuget: Microsoft.Windows.CsWin32, 0.1.691-beta"
#r directive can be used in F# Interactive, C# scripting and .NET Interactive. Copy this into the interactive tool or source code of the script to reference the package.
// Install Microsoft.Windows.CsWin32 as a Cake Addin
#addin nuget:?package=Microsoft.Windows.CsWin32&version=0.1.691-beta&prerelease

// Install Microsoft.Windows.CsWin32 as a Cake Tool
#tool nuget:?package=Microsoft.Windows.CsWin32&version=0.1.691-beta&prerelease
The NuGet Team does not provide support for this client. Please contact its maintainers for support.

C#/Win32 P/Invoke Source Generator

A source generator to add a user-defined set of Win32 P/Invoke methods and supporting types to a C# project.

NuGet (prerelease) NuGet (daily)

Build Status


  • Rapidly add P/Invoke methods and supporting types to your C# project.
  • No bulky assemblies to ship alongside your application.
  • SafeHandle-types automatically generated.
  • Generates xml documentation based on and links back to

Animation demonstrating p/invoke code generation


The .NET 5 SDK or Visual Studio 2019 Update 8 (16.8) for the C# compiler that added support for Source Generators. The experience with source generators in Visual Studio is still improving, and is noticeably better in VS 16.9. WPF projects have additional requirements.

In addition, some generated code may require use of the C# 9 language version (<LangVersion>9</LangVersion>) in your project file. See issue #4 for more on this.

See dotnet/pinvoke for precompiled NuGet packages with Win32 P/Invokes.


Install the Microsoft.Windows.CsWin32 package:

dotnet add package Microsoft.Windows.CsWin32 --prerelease

Tip: Remove the IncludeAssets metadata from the package reference so that you get better code generation by allowing nuget to bring in the System.Memory package as a transitive dependency.

 <PackageReference Include="Microsoft.Windows.CsWin32" Version="0.1.647-beta">
-  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

Your project must allow unsafe code to support the generated code that will likely use pointers. This does not automatically make all your code unsafe. Use of the unsafe keyword is required anywhere you use pointers. The source generator NuGet package sets the default value of the AllowUnsafeBlocks property for your project to true, but if you explicitly set it to false in your project file, generated code may produce compiler errors.

Create a NativeMethods.txt file in your project directory that lists the APIs to generate code for. Each line may consist of one of the following:

  • Exported method name (e.g. CreateFile). This may include the A or W suffix, where applicable. This may be qualified with a namespace but is only recommended in cases of ambiguity, which CsWin32 will prompt where appropriate.
  • A namespace to generate all APIs from (e.g. Windows.Win32.Storage.FileSystem would search the metadata for all APIs within that namespace and generate them).
  • Module name followed by .* to generate all methods exported from that module (e.g. Kernel32.*).
  • The name of a struct, enum, constant or interface to generate. This may be qualified with a namespace but is only recommended in cases of ambiguity, which CsWin32 will prompt where appropriate.
  • A prefix shared by many constants, followed by *, to generate all constants that share that prefix (e.g. ALG_SID_MD*).
  • A comment (i.e. any line starting with //) or white space line, which will be ignored.

When generating any type or member, all supporting types will also be generated.

Generated code is added directly in the compiler. An IDE may make this generated code available to view through code navigation commands (e.g. Go to Definition) or a tree view of source files that include generated source files.

Assuming default settings and a NativeMethods.txt file with content that includes CreateFile, the P/Invoke methods can be found on the Windows.Win32.PInvoke class, like this:

using Windows.Win32;


Constants are defined on the same class as the p/invoke methods (by default, the Windows.Win32.PInvoke class).

Other supporting types are defined within or under the Windows.Win32 namespace. Discovery of the namespace for a given type can be done with the Go To All feature (Ctrl+T) in Visual Studio with the type name as the search query.

Customizing generated code

Several aspects of the generated code can be customized, including:

  • The name of the class(es) that declare p/invoke methods
  • The namespace that declares all interop types
  • Whether to emit interop types as public or internal
  • Whether to emit ANSI functions as well where Wide character functions also exist
  • Set PreserveSig for COM interfaces or individual members
  • Force generation of blittable structs, COM structs instead of interfaces (for super high performance with 0 GC pressure), etc.

To configure these settings, create a NativeMethods.json file in your project directory. Specifying the $schema property adds completions, descriptions and validation in many JSON editors.

  "$schema": "",
  "emitSingleFile": false

Most generated types include the partial modifier so you can add your own members to that type within your code.

When you need to replace a generated type, simply copy and paste it from generated code into your own source files and remove the partial modifier. Be sure to keep the name and namespace exactly the same. CsWin32 will notice that your project already declares the type and skip generating it, but generate everything else. Note that if that type is the only thing that references some other generated type, CsWin32 will stop generating that type too. To keep CsWin32 generating the referred types you need, add them explicitly to NativeMethods.txt.

Newer metadata

To update the metadata used as the source for code generation, you may install a newer Microsoft.Windows.SDK.Win32Metadata package:

dotnet add package Microsoft.Windows.SDK.Win32Metadata --prerelease

Alternatively, you may set the MicrosoftWindowsSdkWin32MetadataBasePath property in your project file to the path of the directory containing Windows.Win32.winmd:


Consuming daily builds

Can't wait for the next release to try out a bug fix? Follow these steps to consume directly from our daily build.

Just add this package feed to your nuget.config file:

<add key="winsdk" value="" />
Product Versions
.NET net5.0 net5.0-windows net6.0 net6.0-android net6.0-ios net6.0-maccatalyst net6.0-macos net6.0-tvos net6.0-windows
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Xamarin.Mac xamarinmac
Xamarin.TVOS xamarintvos
Xamarin.WatchOS xamarinwatchos
Compatible target framework(s)
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Learn more about Target Frameworks and .NET Standard.

NuGet packages

This package is not used by any NuGet packages.

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Version Downloads Last updated
0.2.1-beta 846 6/6/2022
0.1.691-beta 1,249 5/19/2022
0.1.689-beta 73 5/19/2022
0.1.647-beta 2,785 4/26/2022
0.1.646-beta 75 4/25/2022
0.1.635-beta 11,251 1/27/2022
0.1.619-beta 5,341 11/15/2021
0.1.588-beta 8,152 9/20/2021
0.1.584-beta 163 9/18/2021
0.1.560-beta 311 9/8/2021
0.1.506-beta 3,683 6/28/2021
0.1.422-beta 2,732 3/17/2021
0.1.378-beta 1,313 2/24/2021
0.1.319-beta 4,169 1/21/2021