# Integrate with external services

> Extend Cloud Code modules with external services using NuGet packages or HTTP clients.

You can integrate Cloud Code modules with external services.

To handle custom data types, you can implement [Custom JSON Serialization](./initialize-modules/custom-serialization.md).

## Use NuGet packages

Cloud Code modules are C# library projects that live in the .NET ecosystem, so they use the [NuGet package manager](https://learn.microsoft.com/en-us/nuget/) to install dependencies. This means that you can use any external NuGet package in your Cloud Code modules.

To view the available NuGet packages, refer to the [NuGet package library](https://www.nuget.org/).

## Call out to external APIs

You can also call out to any external APIs.
The sample below calls out to a [Cat Facts API](https://catfact.ninja/#/facts/getrandomfact) to get a random cat fact.

1. Declare a `CatFactsApi` class to handle the API call.

   ```csharp
   using Newtonsoft.Json;
   using RestSharp;
   using Unity.Services.CloudCode.Core;
   using Unity.Services.CloudCode.Shared;

   namespace CatFacts;

   public interface ICatFactsApi
   {
       public Task<CatFactsApiResponse?> GetCatFact();
   }

   public class CatFactsApiResponse
   {
       public string fact { get; set; }
       public int length { get; set; }
   }

   public class CatFactsApi : ICatFactsApi
   {
       private readonly RestClient _httpClient;

       public CatFactsApi()
       {
           // It's important to only create one RestClient per service in order to avoid creating and destroying too many network connections which could hurt performance
           _httpClient = new RestClient("https://catfact.ninja/fact");
       }

       public async Task<CatFactsApiResponse?> GetCatFact()
       {
           var request = new RestRequest();

           try
           {
               var res = await _httpClient.ExecuteGetAsync(request);
               return JsonConvert.DeserializeObject<CatFactsApiResponse?>(res.Content);
           }
           catch (ApiException e)
           {
               throw new Exception($"Failed to get cat fact: {e.Message}");
           }
       }
   }
   ```

2. Declare the `CatFactsApi` class as a singleton in the `ModuleConfig` class.

   ```csharp
       public class ModuleConfig : ICloudCodeSetup
       {
           public void Setup(ICloudCodeConfig config)
           {
               config.Dependencies.AddSingleton<ICatFactsApi>(new CatFactsApi());
           }
       }
   ```

3. Declare a `GetCatFact` function that will call the `GetCatFact` method of the `CatFactsApi` class:

   ```csharp
   using Microsoft.Extensions.DependencyInjection;
   using Microsoft.Extensions.Logging;
   using Unity.Services.CloudCode.Core;
   using Unity.Services.CloudCode.Shared;

   namespace CatFacts;

   public class CatFactsSample
   {
       private static ILogger<CatFactsSample> _logger;
       public CatFactsSample(ILogger<CatFactsSample> logger)
       {
           _logger = logger;
       }

       [CloudCodeFunction("GetCatFact")]
       public async Task<CatFactsApiResponse?> GetCatFact(ICatFactsApi catFactsApi)
       {
           try
           {
               var fact = await catFactsApi.GetCatFact();
               _logger.LogInformation("Cat fact: {fact}", fact?.fact);

               return fact;

           }
           catch (ApiException e)
           {
               _logger.LogError("Failed to get cat fact. Error: {Error}", e.Message);
               throw new Exception($"Failed to get cat fact: {e.Message}");
           }
       }

       public class ModuleConfig : ICloudCodeSetup
       {
           public void Setup(ICloudCodeConfig config)
           {
               config.Dependencies.AddSingleton<ICatFactsApi>(new CatFactsApi());
           }
       }
   }
   ```

4. Call the `GetCatFact` function from your game client. The function returns a random cat fact:

   ```json
   {
       "output": {
           "fact": "The Amur leopard is one of the most endangered animals in the world.",
           "length": 68
       }
   }
   ```

For information on how to integrate with Unity services, refer to [Integration with other Unity services](./unity-services-integration.md).