# HostingGrainExtensions.AddGrainExtension(ISiloBuilder)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.runtime/orleans.hosting.hostinggrainextensions/) | [Methods](/orleans/docs/api/csharp/microsoft.orleans.runtime/orleans.hosting.hostinggrainextensions/methods/)

[Source](https://github.com/dotnet/orleans/blob/e4e752cedecc2976811db49802c7a999b1f1c704/src/Orleans.Runtime/Hosting/HostingGrainExtensions.cs#L21)

```csharp
public static ISiloBuilder AddGrainExtension<TExtensionInterface, TExtension>(this ISiloBuilder builder)
```

Registers a grain extension implementation for the specified interface.

### Parameters

- `builder` (`ISiloBuilder`)