Accept Payments with Paystack in ASP.NET Core

Add your Paystack credentials to appsettings.json:

{
  "Paystack": {
    "SecretKey": "sk_test_xxxxxxxxxxxx",
    "PublicKey": "pk_test_xxxxxxxxxxxx",
    "BaseUrl": "https://api.paystack.co"
  }
}

Register a named HttpClient in Program.cs:

// Program.cs
builder.Services.AddHttpClient("Paystack", (provider, client) =>
{
    var config = provider.GetRequiredService<IConfiguration>();
    var secretKey = config["Paystack:SecretKey"];
    client.BaseAddress = new Uri("https://api.paystack.co/");
    client.DefaultRequestHeaders.Authorization =
        new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", secretKey);
    client.DefaultRequestHeaders.Accept.Add(
        new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
});

// Controllers/PaymentController.cs
using System.Text;
using System.Text.Json;
using Microsoft.AspNetCore.Mvc;

[ApiController]
[Route("api/[controller]")]
public class PaymentController : ControllerBase
{
    private readonly IHttpClientFactory _httpClientFactory;
    private readonly IConfiguration _config;

    public PaymentController(IHttpClientFactory httpClientFactory, IConfiguration config)
    {
        _httpClientFactory = httpClientFactory;
        _config = config;
    }

    [HttpPost("initialize")]
    public async Task<IActionResult> Initialize([FromBody] InitializeRequest req)
    {
        if (string.IsNullOrWhiteSpace(req.Email))
            return BadRequest(new { error = "Email is required" });

        var reference = "dotnet_" + DateTimeOffset.UtcNow.ToUnixTimeMilliseconds() +
                        "_" + Guid.NewGuid().ToString("N")[..6];

        var payload = new
        {
            email = req.Email,
            amount = (long)(req.Amount * 100),  // Convert to kobo
            reference = reference,
            callback_url = _config["Paystack:CallbackUrl"]
        };

        var client = _httpClientFactory.CreateClient("Paystack");
        var json = JsonSerializer.Serialize(payload);
        var content = new StringContent(json, Encoding.UTF8, "application/json");

        var response = await client.PostAsync("transaction/initialize", content);
        var responseBody = await response.Content.ReadAsStringAsync();
        var result = JsonSerializer.Deserialize<JsonElement>(responseBody);

        if (!result.GetProperty("status").GetBoolean())
        {
            return BadRequest(new { error = result.GetProperty("message").GetString() });
        }

        var data = result.GetProperty("data");
        return Ok(new
        {
            authorization_url = data.GetProperty("authorization_url").GetString(),
            access_code = data.GetProperty("access_code").GetString(),
            reference = data.GetProperty("reference").GetString()
        });
    }
}

public record InitializeRequest(string Email, decimal Amount);

// Controllers/PaymentController.cs (continued)

[HttpGet("callback")]
public async Task<IActionResult> Callback([FromQuery] string reference, [FromQuery] string trxref)
{
    var ref_ = reference ?? trxref;

    if (string.IsNullOrWhiteSpace(ref_))
        return BadRequest("Reference missing");

    var client = _httpClientFactory.CreateClient("Paystack");
    var response = await client.GetAsync($"transaction/verify/{Uri.EscapeDataString(ref_)}");
    var responseBody = await response.Content.ReadAsStringAsync();
    var result = JsonSerializer.Deserialize<JsonElement>(responseBody);

    if (!result.GetProperty("status").GetBoolean())
        return BadRequest("Verification failed");

    var data = result.GetProperty("data");
    var txStatus = data.GetProperty("status").GetString();

    if (txStatus != "success")
        return BadRequest(new { status = txStatus });

    var amount = data.GetProperty("amount").GetInt64();
    var currency = data.GetProperty("currency").GetString();

    // Grant access, fulfill order, update database
    return Ok(new { verified = true, amount = amount / 100m, currency, reference = ref_ });
}

If you prefer Minimal APIs in .NET 6+:

// Program.cs additions
app.MapPost("/api/pay", async (InitializeRequest req, IHttpClientFactory factory, IConfiguration config) =>
{
    var reference = "dotnet_" + DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
    var payload = new { email = req.Email, amount = (long)(req.Amount * 100), reference };

    var client = factory.CreateClient("Paystack");
    var response = await client.PostAsJsonAsync("transaction/initialize", payload);
    var result = await response.Content.ReadFromJsonAsync<JsonElement>();

    if (!result.GetProperty("status").GetBoolean())
        return Results.BadRequest(result.GetProperty("message").GetString());

    var data = result.GetProperty("data");
    return Results.Ok(new
    {
        authorization_url = data.GetProperty("authorization_url").GetString(),
        reference = data.GetProperty("reference").GetString()
    });
});

app.MapGet("/api/pay/callback", async (string reference, IHttpClientFactory factory) =>
{
    var client = factory.CreateClient("Paystack");
    var result = await client.GetFromJsonAsync<JsonElement>($"transaction/verify/{reference}");

    if (result.GetProperty("data").GetProperty("status").GetString() != "success")
        return Results.BadRequest("Payment not verified");

    return Results.Ok(new { verified = true, reference });
});

This guide is part of the Paystack integration guides by language and framework series.

Next: Handle Paystack Webhooks in ASP.NET Core

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