1. Define providers in appsettings.json/appsettings.*.json

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   {
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     "ProviderSettings": {
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       "Gemini": {
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         "Endpoint": "https://generativelanguage.googleapis.com/v1beta",
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         "ApiKey": "",
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         "DefaultModel": "gemini-2.0-flash-exp"
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       },
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       "Mistral": {
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         "Endpoint": "https://api.mistral.ai/v1",
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         "ApiKey": "",
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         "DefaultModel": "mistral-large-2407"
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       },
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       "OpenRouter": {
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         "Endpoint": "https://openrouter.ai/api/v1",
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         "ApiKey": "",
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         "DefaultModel": "google/gemini-2.0-pro-exp-02-05:free"
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       },
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       "Ollama": {
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         "Endpoint": "http://127.0.0.1:11434/v1",
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         "ApiKey": "",
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         "DefaultModel": "command-r7b"
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       }
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     }
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   }
   

2. Create config classes

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   public class ProviderConfiguration
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   {
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       public string Endpoint { get; set; } = string.Empty;
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       public string ApiKey { get; set; } = string.Empty;
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       public string DefaultModel { get; set; } = string.Empty;
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   }
   

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   public class ProviderSettings
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   {
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       public ProviderConfiguration Gemini { get; set; } = default!;
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       public ProviderConfiguration Mistral { get; set; } = default!;
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       public ProviderConfiguration OpenRouter { get; set; } = default!;
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       public ProviderConfiguration Ollama { get; set; } = default!;
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   }
   

3. Register config in Program.cs

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   builder.Services.Configure<ProviderSettings>(
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       builder.Configuration.GetSection(nameof(ProviderSettings)));
   

4. Install OpenAI package

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   dotnet add package OpenAI
   

5. Use in endpoint

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   app.MapGet("", async (
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       IOptions<ProviderSettings> options,
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       string prompt,
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       CancellationToken cancellationToken) =>
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   {
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       var provider = options.Value.Gemini;
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       var client = new ChatClient(
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           provider.DefaultModel,
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           new ApiKeyCredential(provider.ApiKey),
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           new OpenAIClientOptions { Endpoint = new Uri(provider.Endpoint) }
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       );
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       var result = await client.CompleteChatAsync([prompt], cancellationToken);
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       return Results.Ok(result.Value.Content);
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   });
   

NOTE

You can switch to other providers like options.Value.Mistral, options.Value.Ollama, etc.

References#

• OpenAI nuget package