Xsd2CSharp turns an XSD schema into hand-rolled C# classes for reading and writing XML - no runtime reflection, no System.Xml.Serialization.XmlSerializer.

• xsd:choice and substitution groups become C# 15 union types instead of a pile of nullable properties, so exactly one branch can ever be set and the compiler enforces it.
• Every generated type implements IXmlSerializable itself, with the read/write logic emitted directly into the class - there's no attribute-driven reflection step at load time.
• xsd:complexContent extension/restriction becomes real C# inheritance.
• xsd:import/xsd:include are followed automatically, and each distinct XSD namespace gets its own C# sub-namespace.

You can use it two ways:

• CLI (xsd2cs) - generate .cs files once and commit them like any other source.
• Roslyn incremental source generator - point it at your .xsd files via <AdditionalFiles> and it regenerates the model on every build.

Generated code requires <LangVersion>preview</LangVersion> and a .NET 11+ SDK in the consuming project, because it uses C# 15 union types.

Requires the .NET 11 SDK (preview) - the test project targets net11.0 and generated code needs LangVersion=preview.

dotnet build Xsd2CSharp.sln

dotnet test tests/Xsd2CSharp.Tests/Xsd2CSharp.Tests.csproj

Run it directly from source:

dotnet run --project src/Xsd2CSharp.Cli -- <schema.xsd> [<more.xsd> ...] -o <output-dir> -n <namespace>

Or install it as a local/global .NET tool:

dotnet pack src/Xsd2CSharp.Cli -c Release
dotnet tool install --global --add-source src/Xsd2CSharp.Cli/bin/Release xsd2cs
xsd2cs <schema.xsd> -o <output-dir> -n <namespace>

xsd2cs <schema.xsd> [<more.xsd> ...] [-o <output-dir>] [-n <namespace>] [--namespace-map <xsd-ns>=<segment>]...

  -o, --output        Output directory (default: current directory)
  -n, --namespace     Base C# namespace for generated types (default: derived from the first schema's file name)
  --namespace-map     Map one XSD targetNamespace URI to a C# sub-namespace segment under -n, e.g.
                       --namespace-map http://www.opengis.net/gml/3.2=Gml
                       Repeatable. Namespaces not covered by this get an auto-derived segment name;
                       pass an empty segment (e.g. "http://...=") to fold that namespace into the base namespace instead.
                       Has no effect on a namespace that's already the root - that one always maps to -n's value.
  -h, --help           Show this help

Only pass the root schema file(s) - xsd:import/xsd:include are resolved automatically. The output folder layout mirrors the full C# namespace, e.g. with -n NeTEx.Model a root-namespace type goes into NeTEx/Model/Foo.cs and a GML-imported one into NeTEx/Model/Gml/Bar.cs. A small runtime support file (Xsd2CSharpRuntime.cs) is written alongside the model - it's required at compile time by every generated class.

Reference the generator project as an analyzer and add your schema(s) as AdditionalFiles:

<PropertyGroup>
  <LangVersion>preview</LangVersion>
</PropertyGroup>

<ItemGroup>
  <AdditionalFiles Include="Schemas\**\*.xsd" Xsd2CSharpNamespace="MyApp.Model" />
  <CompilerVisibleItemMetadata Include="AdditionalFiles" MetadataName="Xsd2CSharpNamespace" />
  <CompilerVisibleItemMetadata Include="AdditionalFiles" MetadataName="Xsd2CSharpNamespaceMap" />
</ItemGroup>

<ItemGroup>
  <ProjectReference Include="path\to\Xsd2CSharp.SourceGenerator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
</ItemGroup>

The base namespace for a schema's generated types comes from, in order: the Xsd2CSharpNamespace metadata on its <AdditionalFiles> item, otherwise {RootNamespace}.{PascalCase(file name)}. Xsd2CSharpNamespaceMap (format: uri1=Segment1;uri2=Segment2) overrides the auto-derived sub-namespace segment for specific XSD namespaces, same as the CLI's --namespace-map. The generator adds the same runtime support file as a generated source automatically.

AGPL-3.0 - see LICENSE.txt.