OpenAI

Features 🔥

• Fully generated C# SDK based on official OpenAI OpenAPI specification using AutoSDK
• Same day update to support new features
• Updated and supported automatically if there are no breaking changes
• Contains a supported list of constants such as current prices, models, and other
• Source generator to define functions natively through C# interfaces
• All modern .NET features - nullability, trimming, NativeAOT, etc.
• Support .Net Framework/.Net Standard 2.0
• Support all OpenAI API endpoints including completions, chat, embeddings, images, assistants and more.
• Regularly tested for compatibility with popular custom providers like OpenRouter/DeepSeek/Ollama/LM Studio and many others

Documentation

Examples and documentation can be found here: https://tryagi.github.io/OpenAI/

Usage

using var api = new OpenAiApi("API_KEY");
string response = await api.Chat.CreateChatCompletionAsync(
    messages: ["Generate five random words."],
    model: CreateChatCompletionRequestModel.Gpt4oMini);
Console.WriteLine(response); // "apple, banana, cherry, date, elderberry"

var enumerable = api.Chat.CreateChatCompletionAsStreamAsync(
    messages: ["Generate five random words."],
    model: CreateChatCompletionRequestModel.Gpt4oMini);

await foreach (string response in enumerable)
{
    Console.WriteLine(response);
}

It uses three implicit conversions:

• from string to ChatCompletionRequestUserMessage. It will always be converted to the user message.
• from ChatCompletionResponseMessage to string . It will always contain the first choice message content.
• from CreateChatCompletionStreamResponse to string . It will always contain the first delta content.

You still can use the full response objects if you need more information, just replace string response to var response.

Tools

using OpenAI;
using CSharpToJsonSchema;

public enum Unit
{
    Celsius,
    Fahrenheit,
}

public class Weather
{
    public string Location { get; set; } = string.Empty;
    public double Temperature { get; set; }
    public Unit Unit { get; set; }
    public string Description { get; set; } = string.Empty;
}

[GenerateJsonSchema(Strict = true)] // false by default. You can't use parameters with default values in Strict mode.
public interface IWeatherFunctions
{
    [Description("Get the current weather in a given location")]
    public Task<Weather> GetCurrentWeatherAsync(
        [Description("The city and state, e.g. San Francisco, CA")] string location,
        Unit unit,
        CancellationToken cancellationToken = default);
}

public class WeatherService : IWeatherFunctions
{
    public Task<Weather> GetCurrentWeatherAsync(string location, Unit unit = Unit.Celsius, CancellationToken cancellationToken = default)
    {
        return Task.FromResult(new Weather
        {
            Location = location,
            Temperature = 22.0,
            Unit = unit,
            Description = "Sunny",
        });
    }
}

using var api = new OpenAiApi("API_KEY");

var service = new WeatherService();
var tools = service.AsTools().AsOpenAiTools();

var messages = new List<ChatCompletionRequestMessage>
{
    "You are a helpful weather assistant.".AsSystemMessage(),
    "What is the current temperature in Dubai, UAE in Celsius?".AsUserMessage(),
};
var model = CreateChatCompletionRequestModel.Gpt4oMini;
var result = await api.Chat.CreateChatCompletionAsync(
    messages,
    model: model,
    tools: tools);
var resultMessage = result.Choices.First().Message;
messages.Add(resultMessage.AsRequestMessage());

foreach (var call in resultMessage.ToolCalls)
{
    var json = await service.CallAsync(
        functionName: call.Function.Name,
        argumentsAsJson: call.Function.Arguments);
    messages.Add(json.AsToolMessage(call.Id));
}

var result = await api.Chat.CreateChatCompletionAsync(
    messages,
    model: model,
    tools: tools);
var resultMessage = result.Choices.First().Message;
messages.Add(resultMessage.AsRequestMessage());

> System: 
You are a helpful weather assistant.
> User: 
What is the current temperature in Dubai, UAE in Celsius?
> Assistant: 
call_3sptsiHzKnaxF8bs8BWxPo0B:
GetCurrentWeather({"location":"Dubai, UAE","unit":"celsius"})
> Tool(call_3sptsiHzKnaxF8bs8BWxPo0B):
{"location":"Dubai, UAE","temperature":22,"unit":"celsius","description":"Sunny"}
> Assistant: 
The current temperature in Dubai, UAE is 22°C with sunny weather.

Structured Outputs

using OpenAI;

using var api = new OpenAiApi("API_KEY");

var response = await api.Chat.CreateChatCompletionAsAsync<Weather>(
    messages: ["Generate random weather."],
    model: CreateChatCompletionRequestModel.Gpt4oMini,
    jsonSerializerOptions: new JsonSerializerOptions
    {
        Converters = {new JsonStringEnumConverter()},
    });
// or (if you need trimmable/NativeAOT version)
var response = await api.Chat.CreateChatCompletionAsAsync(
    jsonTypeInfo: SourceGeneratedContext.Default.Weather,
    messages: ["Generate random weather."],
    model: CreateChatCompletionRequestModel.Gpt4oMini);

// response.Value1 contains the structured output
// response.Value2 contains the CreateChatCompletionResponse object

Weather:
Location: San Francisco, CA
Temperature: 65
Unit: Fahrenheit
Description: Partly cloudy with a light breeze and occasional sunshine.
Raw Response:
{"Location":"San Francisco, CA","Temperature":65,"Unit":"Fahrenheit","Description":"Partly cloudy with a light breeze and occasional sunshine."}

Additional code for trimmable/NativeAOT version:

[JsonSourceGenerationOptions(Converters = [typeof(JsonStringEnumConverter<Unit>)])]
[JsonSerializable(typeof(Weather))]
public partial class SourceGeneratedContext : JsonSerializerContext;

Custom providers

using OpenAI;

using var api = CustomProviders.GitHubModels("GITHUB_TOKEN");
using var api = CustomProviders.Azure("API_KEY", "ENDPOINT");
using var api = CustomProviders.DeepInfra("API_KEY");
using var api = CustomProviders.Groq("API_KEY");
using var api = CustomProviders.XAi("API_KEY");
using var api = CustomProviders.DeepSeek("API_KEY");
using var api = CustomProviders.Fireworks("API_KEY");
using var api = CustomProviders.OpenRouter("API_KEY");
using var api = CustomProviders.Together("API_KEY");
using var api = CustomProviders.Perplexity("API_KEY");
using var api = CustomProviders.SambaNova("API_KEY");
using var api = CustomProviders.Mistral("API_KEY");
using var api = CustomProviders.Codestral("API_KEY");
using var api = CustomProviders.Cerebras("API_KEY");
using var api = CustomProviders.Ollama();
using var api = CustomProviders.LmStudio();

Constants

All tryGetXXX methods return null if the value is not found.
There also non-try methods that throw an exception if the value is not found.

using OpenAI;

// You can try to get the enum from string using:
var model = CreateChatCompletionRequestModelExtensions.ToEnum("gpt-4o") ?? throw new Exception("Invalid model");

// Chat
var model = CreateChatCompletionRequestModel.Gpt4oMini;
double? priceInUsd = model.TryGetPriceInUsd(
    inputTokens: 500,
    outputTokens: 500)
double? priceInUsd = model.TryGetFineTunePriceInUsd(
    trainingTokens: 500,
    inputTokens: 500,
    outputTokens: 500)
int contextLength = model.TryGetContextLength() // 128_000
int outputLength = model.TryGetOutputLength() // 16_000

// Embeddings
var model = CreateEmbeddingRequestModel.TextEmbedding3Small;
int? maxInputTokens = model.TryGetMaxInputTokens() // 8191
double? priceInUsd = model.TryGetPriceInUsd(tokens: 500)

// Images
double? priceInUsd = CreateImageRequestModel.DallE3.TryGetPriceInUsd(
    size: CreateImageRequestSize.x1024x1024,
    quality: CreateImageRequestQuality.Hd)

// Speech to Text
double? priceInUsd = CreateTranscriptionRequestModel.Whisper1.TryGetPriceInUsd(
    seconds: 60)

// Text to Speech
double? priceInUsd = CreateSpeechRequestModel.Tts1Hd.TryGetPriceInUsd(
    characters: 1000)

Support

Priority place for bugs: https://github.com/tryAGI/OpenAI/issues
Priority place for ideas and general questions: https://github.com/tryAGI/OpenAI/discussions
Discord: https://discord.gg/Ca2xhfBf3v

Acknowledgments

This project is supported by JetBrains through the Open Source Support Program.

This project is supported by CodeRabbit through the Open Source Support Program.