How do I integrate Azure OpenAI with an ASP.NET Core application?

Integrating Azure OpenAI into your ASP.NET Core application involves four main stages: resource setup, configuration, client registration, and implementation.

1. Azure Setup

Before writing code, you need the infrastructure in place:

• Create Resource: In the Azure Portal, search for Azure OpenAI and create a resource.

• Deploy a Model: Go to Azure AI Foundry (formerly Azure OpenAI Studio), select Deployments, and create a new deployment (e.g., using the gpt-4o or gpt-3.5-turbo model).

• Collect Credentials: From the Keys and Endpoint tab of your resource, copy your Endpoint URL and API Key.

2. Project Configuration

Install the official Azure SDK via the NuGet Package Manager or CLI:

dotnet add package Azure.AI.OpenAI

Store your credentials securely in appsettings.json (for development) or use Environment Variables/Azure Key Vault (for production):

{
  "AzureOpenAI": {
    "Endpoint": "https://your-resource-name.openai.azure.com/",
    "ApiKey": "YOUR_API_KEY_HERE",
    "DeploymentName": "chat-gpt-deployment"
  }
}

3. Service Registration

In your Program.cs, register the AzureOpenAIClient (or the specific ChatClient from the Microsoft.Extensions.AI library if using the latest 2026 abstractions) as a Singleton to ensure efficient connection pooling.

using Azure;
using Azure.AI.OpenAI;
using Microsoft.Extensions.AI;

var builder = WebApplication.CreateBuilder(args);

// Register the Client
builder.Services.AddSingleton(sp => 
{
    var config = builder.Configuration.GetSection("AzureOpenAI");
    return new AzureOpenAIClient(
        new Uri(config["Endpoint"]), 
        new AzureKeyCredential(config["ApiKey"]));
});

4. Implementation in a Controller or Service

Inject the client into your controller to handle user requests asynchronously.

[ApiController]
[Route("api/[controller]")]
public class ChatController : ControllerBase
{
    private readonly AzureOpenAIClient _client;
    private readonly string _deploymentName;

    public ChatController(AzureOpenAIClient client, IConfiguration config)
    {
        _client = client;
        _deploymentName = config["AzureOpenAI:DeploymentName"];
    }

    [HttpPost("ask")]
    public async Task AskQuestion([FromBody] string userPrompt)
    {
        var chatClient = _client.GetChatClient(_deploymentName);
        var response = await chatClient.CompleteChatAsync(userPrompt);

        return Ok(response.Value.Content);
    }
}