.NET MAUI app that connects to an AI service (like ChatGPT via OpenAI API)

Create a cross-platform MAUI app (Windows, Android, macOS, iOS) that:

• Accepts a user prompt.

• Sends it to an AI engine (e.g., OpenAI).

• Displays the AI response.

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📦 Prerequisites

• .NET 8 SDK

• Visual Studio 2022/2025 with MAUI workload

• An API Key (e.g., from OpenAI)

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🔧 Step-by-Step Setup

1. Create the MAUI App

dotnet new maui -n MauiAIChatApp
cd MauiAIChatApp

2. Add Dependencies

Edit the .csproj to include System.Net.Http.Json (or add OpenAI.Net via NuGet for simplicity):

dotnet add package OpenAI.Net --version 7.0.1

OR, if using direct HTTP:

dotnet add package Newtonsoft.Json

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3. Add the API Service

Create a service to call the AI engine.

🔹 Services/OpenAIService.cs

using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;

public class OpenAIService
{
    private readonly HttpClient _httpClient;
    private const string apiKey = "sk-REPLACE_WITH_YOUR_KEY";
    private const string endpoint = "https://api.openai.com/v1/chat/completions";

    public OpenAIService()
    {
        _httpClient = new HttpClient();
        _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);
    }

    public async Task<string> AskChatGPT(string userPrompt)
    {
        var requestBody = new
        {
            model = "gpt-3.5-turbo",
            messages = new[]
            {
                new { role = "user", content = userPrompt }
            },
            max_tokens = 100
        };

        var json = JsonSerializer.Serialize(requestBody);
        var content = new StringContent(json, Encoding.UTF8, "application/json");

        var response = await _httpClient.PostAsync(endpoint, content);
        var result = await response.Content.ReadAsStringAsync();

        if (!response.IsSuccessStatusCode)
            return $"Error: {result}";

        using var doc = JsonDocument.Parse(result);
        return doc.RootElement
                  .GetProperty("choices")[0]
                  .GetProperty("message")
                  .GetProperty("content")
                  .GetString()
                  ?.Trim();
    }
}

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4. Update MainPage.xaml UI

<VerticalStackLayout Padding="20" Spacing="20">
    <Label Text="Ask AI Anything" FontSize="24" HorizontalOptions="Center" />
    <Entry x:Name="PromptEntry" Placeholder="Enter your prompt..." />
    <Button Text="Ask" Clicked="OnAskClicked" />
    <ScrollView HeightRequest="300">
        <Label x:Name="ResponseLabel" FontSize="18" />
    </ScrollView>
</VerticalStackLayout>

---

5. Update MainPage.xaml.cs

public partial class MainPage : ContentPage
{
    private readonly OpenAIService _openAIService;

    public MainPage()
    {
        InitializeComponent();
        _openAIService = new OpenAIService();
    }

    private async void OnAskClicked(object sender, EventArgs e)
    {
        var prompt = PromptEntry.Text;
        if (string.IsNullOrWhiteSpace(prompt)) return;

        ResponseLabel.Text = "Thinking...";
        var response = await _openAIService.AskChatGPT(prompt);
        ResponseLabel.Text = response;
    }
}

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✅ Run the App

dotnet build
dotnet maui run