Building Enterprise LLM Apps with .NET

.NET is Microsoft’s battle-tested framework trusted by Fortune 500 companies. It’s now easier than ever to build LLM apps. You get:


Battle-Tested Security	Built-in identity management, secret rotation, and compliance standards
Production Performance	High-throughput processing with advanced memory management
Azure Integration	Seamless Azure OpenAI and Active Directory support

Combined with Portkey’s enterprise features, you get everything needed for mission-critical LLM deployments. Monitor costs, ensure reliability, maintain compliance, and scale with confidence.

Portkey Features


Complete Observability	Monitor costs, latency, and performance metrics
Provider Flexibility	Route to 250+ LLMs (like Claude, Gemini, Llama, self-hosted etc.) without code changes
Smart Caching	Reduce costs & time by caching frequent requests
High Reliability	Automatic fallback and load balancing across providers
Prompt Management	Use Portkey as a centralized hub to version, experiment with prompts, and call them using a single ID
Continuous Improvement	Improve your app by capturing and analyzing user feedback
Enterprise Ready	Budget controls, rate limits, model-provisioning, and role-based access

Implementation Overview

Install OpenAI SDK
Create Portkey client by extending OpenAI client
Use the client in your application to make requests

1. Install the NuGet package

Add the OpenAI NuGet package to your .NET project:

dotnet add package OpenAI

2. Create Portkey Client Extension

The OpenAI package does not support directly modifying the base URL or passing additional headers. So, we write a simple function to extend OpenAI’s ChatClient to create a new PortkeyClient.

using OpenAI;
using OpenAI.Chat;
using System.ClientModel;
using System.ClientModel.Primitives;

public static class PortkeyClient
{
    private class HeaderPolicy : PipelinePolicy
    {
        private readonly Dictionary<string, string> _headers;
        public HeaderPolicy(Dictionary<string, string> headers) => _headers = headers;

        public override void Process(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int index)
        {
            foreach (var header in _headers) message.Request.Headers.Set(header.Key, header.Value);
            if (index < pipeline.Count) pipeline[index].Process(message, pipeline, index + 1);
        }

        public override ValueTask ProcessAsync(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int index)
        {
            Process(message, pipeline, index);
            return ValueTask.CompletedTask;
        }
    }

    public static ChatClient CreateChatClient(Dictionary<string, string> headers, string model)
    {
        var options = new OpenAIClientOptions { Endpoint = new Uri("https://api.portkey.ai/v1") };
        options.AddPolicy(new HeaderPolicy(headers), PipelinePosition.PerCall);
        return new OpenAIClient(new ApiKeyCredential("dummy"), options).GetChatClient(model);
    }
}

3. Use the Portkey Client

After creating the extension above, you can pass any Portkey supported headers directly while creating the new client.

// Define Portkey headers
var headers = new Dictionary<string, string> {
    // Required headers
    { "x-portkey-api-key", "..." },       // Your Portkey API key
    { "x-portkey-virtual-key", "..." },    // Virtual key for provider

    // Optional headers
    { "x-portkey-trace-id", "my-app" },       // Custom trace identifier
    { "x-portkey-config", "..." },            // Send Config ID
    // Add any other Portkey headers as needed
};

// Create client
var client = PortkeyClient.CreateChatClient(
    headers: headers,
    model: "gpt-4"
);

// Make request
var response = client.CompleteChat(new UserChatMessage("Yellow!"));
Console.WriteLine(response.Value.Content[0].Text);

While we show common headers here, you can pass any Portkey-supported headers to enable features like custom metadata, fallbacks, caching, retries, and more.

4. View Your Request in Portkey Logs

This request will now be logged on Portkey:

End-to-End Example

Save your Azure OpenAI details on Portkey to get a virtual key.

using OpenAI;
using OpenAI.Chat;
using System.ClientModel;
using System.ClientModel.Primitives;

public static class Portkey
{
    private class HeaderPolicy : PipelinePolicy
    {
        private readonly Dictionary<string, string> _headers;
        public HeaderPolicy(Dictionary<string, string> headers) => _headers = headers;

        public override void Process(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int index)
        {
            foreach (var header in _headers) message.Request.Headers.Set(header.Key, header.Value);
            if (index < pipeline.Count) pipeline[index].Process(message, pipeline, index + 1);
        }

        public override ValueTask ProcessAsync(PipelineMessage message, IReadOnlyList<PipelinePolicy> pipeline, int index)
        {
            Process(message, pipeline, index);
            return ValueTask.CompletedTask;
        }
    }

    public static ChatClient CreateChatClient(Dictionary<string, string> headers, string model)
    {
        var options = new OpenAIClientOptions { Endpoint = new Uri("https://api.portkey.ai/v1") };
        options.AddPolicy(new HeaderPolicy(headers), PipelinePosition.PerCall);
        return new OpenAIClient(new ApiKeyCredential("dummy"), options).GetChatClient(model);
    }
}

public class Program
{
    public static void Main()
    {
        var client = Portkey.CreateChatClient(
            headers: new Dictionary<string, string> {
                { "x-portkey-api-key", "PORTKEY API KEY" },
                { "x-portkey-virtual-key", "AZURE VIRTUAL KEY" },
                { "x-portkey-trace-id", "dotnet" }
            },
            model: "dummy" // We pass "dummy" here because for Azure the model can be configured with the virtual key
        );

        Console.WriteLine(client.CompleteChat(new UserChatMessage("1729")).Value.Content[0].Text);
    }
}

More Features

You can also use the PortkeyClient to send Async requests:

var completion = await client.CompleteChatAsync(new UserChatMessage("Hello!"));
Console.WriteLine(completion.Value.Content[0].Text);

Next Steps

Need Help?

Ping the Portkey team on our Developer Forum or email us at [email protected]

API Reference

Chat Completions

Portkey Prompts

Embeddings

Images

Audio

Other APIs

Completions

Moderations

Fine-tuning

Batch

Files

Assistants

C# (.NET)

Building Enterprise LLM Apps with .NET

Portkey Features

Implementation Overview

1. Install the NuGet package

2. Create Portkey Client Extension

3. Use the Portkey Client

4. View Your Request in Portkey Logs

End-to-End Example

More Features

Next Steps

Need Help?

API Reference

Chat Completions

Portkey Prompts

Embeddings

Images

Audio

Other APIs

Completions

Moderations

Fine-tuning

Batch

Files

Assistants

​Building Enterprise LLM Apps with .NET

​Portkey Features

​Implementation Overview

​1. Install the NuGet package

​2. Create Portkey Client Extension

​3. Use the Portkey Client

​4. View Your Request in Portkey Logs

​End-to-End Example

​More Features

​Next Steps

​Need Help?

Building Enterprise LLM Apps with .NET

Portkey Features

Implementation Overview

1. Install the NuGet package

2. Create Portkey Client Extension

3. Use the Portkey Client

4. View Your Request in Portkey Logs

End-to-End Example

More Features

Next Steps

Need Help?