Adding Webhook Support in C# v4 SDKs (Beta)

C# v4 SDKs now understand the webhooks declared in your OpenAPI specification. The SDK generates a typed event parser and, when the specification describes a signing scheme, a signature verifier, so consumers can receive and verify events with the same type safety they get when calling your API.

Details

Each webhook event's payload becomes a typed model. The parser reads the discriminator your specification names, from the request body or a header, and returns an event whose Type names the event and whose Payload exposes one TryGet accessor per event.

When the specification describes how events are signed, the SDK also generates a signature verifier configured through WebhookOptions: the shared Secret, a ReplayTolerance where the specification sets one, and a TimeProvider. Generated Add{Api}Webhooks and Add{Api}WebhookSignatureVerifier methods register the parser and the verifier with ASP.NET Core dependency injection.

Usage Example

Register the parser and the verifier, then verify and parse each incoming request in your webhook endpoint:

builder.Services.AddPaymentsWebhooks();
builder.Services.AddPaymentsWebhookSignatureVerifier(options =>
    options.Secret = builder.Configuration["Payments:WebhookSecret"]);

var app = builder.Build();

app.MapPost("/webhooks/payments", async (HttpRequest http, PaymentsWebhookParser parser,
    PaymentsWebhookSignatureVerifier verifier, CancellationToken cancellationToken) =>
{
    var webhookRequest = await WebhookRequest.FromStream(http.Body, http.Headers, cancellationToken);
    if (!verifier.Verify(webhookRequest))
        return Results.Unauthorized();

    var evt = parser.Parse(webhookRequest);
    if (evt.Type == PaymentsEventType.PaymentStatusUpdated &&
        evt.Payload.TryGetPaymentStatusUpdatedEvent(out var updated))
    {
        Console.WriteLine($"Payment status changed: {updated.Status.Value}");
    }

    return Results.Ok();
});

Parse only deserializes the event, so always call Verify first when your API signs its webhooks.

This feature is available in the C# v4 SDK (beta). Generate it from the APIMatic CLI:

apimatic sdk generate --language=csharp --codegen-version=v4 --stability=beta

For the full set of flags and options, see the APIMatic CLI documentation.