C# / .NET

dotnet add package NoPayn

dotnet add reference path/to/src/NoPayn/NoPayn.csproj

using NoPayn;
using NoPayn.Models;

var nopayn = new NoPaynClient(new NoPaynConfig(
    ApiKey: "your-api-key",
    MerchantId: "your-project"
));

var result = await nopayn.GeneratePaymentUrlAsync(new CreateOrderParams
{
    Amount = 1295,              // €12.95 in cents
    Currency = "EUR",
    MerchantOrderId = "ORDER-001",
    Description = "Premium Widget",
    ReturnUrl = "https://shop.example.com/success",
    FailureUrl = "https://shop.example.com/failure",
    WebhookUrl = "https://shop.example.com/webhook",
    Locale = "en-GB",
    ExpirationPeriod = "PT30M",
});

// Redirect the customer
// result.OrderUrl   → HPP (customer picks payment method)
// result.PaymentUrl → direct link to the first transaction's payment method
// result.Signature  → HMAC-SHA256 for verification
// result.OrderId    → NoPayn order UUID

app.MapPost("/webhook", async (HttpContext ctx) =>
{
    using var reader = new StreamReader(ctx.Request.Body);
    var rawBody = await reader.ReadToEndAsync();
    var verified = await nopayn.VerifyWebhookAsync(rawBody);

    Console.WriteLine(verified.Order.Status); // "completed", "cancelled", etc.
    Console.WriteLine(verified.IsFinal);      // true when the order won't change

    if (verified.Order.Status == "completed")
    {
        // Fulfil the order
    }

    return Results.Ok();
});

public record PaymentUrlResult(
    string OrderId,        // NoPayn order UUID
    string OrderUrl,       // HPP URL
    string? PaymentUrl,    // Direct payment URL (first transaction)
    string Signature,      // HMAC-SHA256 of amount:currency:orderId
    Order Order            // Full order object
);

using NoPayn;

var sig = NoPaynSignature.Generate("your-api-key", 1295, "EUR", "order-uuid");
var ok  = NoPaynSignature.Verify("your-api-key", 1295, "EUR", "order-uuid", sig);

using NoPayn.Exceptions;

try
{
    await nopayn.CreateOrderAsync(new CreateOrderParams { Amount = 100, Currency = "EUR" });
}
catch (ApiException ex)
{
    Console.Error.WriteLine(ex.StatusCode);  // 401, 400, etc.
    Console.Error.WriteLine(ex.ErrorBody);   // Raw API error response
}
catch (NoPaynException ex)
{
    Console.Error.WriteLine(ex.Message);     // Network or parsing error
}