Question: I am working in google api with asp.net c#, My goal is access google api using service account.

I have imported all needed dlls to create [service account](https://developers.google.com/accounts/docs/OAuth2ServiceAccount) to access admin features(admin sdk). 

But i couldn't find ServiceAccountCredential. 

How can i implement this in my project?

Answer: 
Here's how you do it in 2017:

* Go to the [Service Accounts page](https://console.cloud.google.com/iam-admin/serviceaccounts)
* Create a private key for the service account as a JSON file
* Put the downloaded file in your project (for development) or bake it in your build process
* Reference the [Google.Apis.Auth](https://www.nuget.org/packages/Google.Apis.Auth/) package in your code

```
  using (var stream = new FileStream("key.json", FileMode.Open, FileAccess.Read))
  {
      var credential = GoogleCredential.FromStream(stream)
                                       .CreateScoped(scopes)
                                       .UnderlyingCredential as ServiceAccountCredential;

      //profit
  }

```
I am using Xamarin Studio and I have an NUnit test library project (PCL) working on my Mac using ServiceAccountCredential. I just tried to move it to an Android test project (MonoDroid), and ServiceAccountCredential does not exist. ServiceAccount does exist (its ancestral class). So this problem may be related to the compile target, and ServiceAccountCredential not being implemented for your target.