Send WhatsApp messages with C# / .NET

With HttpClient and PostAsJsonAsync, sending a WhatsApp message from .NET takes a few lines — in ASP.NET Core, worker services or Azure Functions.

1. Setup

// .NET 6+ — System.Net.Http.Json is included

2. Send a WhatsApp text message with C# / .NET

The recipient goes in to with the country code (for India, 91 followed by the 10-digit number). The response contains the message id and status.

using System.Net.Http.Json;

var apiKey = "YOUR_API_KEY";
var instanceId = "YOUR_INSTANCE_ID";

using var http = new HttpClient();
http.DefaultRequestHeaders.Add("x-api-key", apiKey);

var response = await http.PostAsJsonAsync(
    $"https://powerapiwa.com/api/v1/instances/{instanceId}/send",
    new { to = "919876543210", type = "text", message = "Hello from .NET" });

Console.WriteLine(await response.Content.ReadAsStringAsync());

Response and errors

Successful calls return {"success": true, ...}. Errors return {"success": false, "error": "..."} with a status code: 401 invalid key, 402 plan expired, 422 invalid payload, 429 daily limit reached. See the full API documentation.

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