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Wrapper for the Yahoo Fantasy Sports API. Includes Authorization and Data Retrieval. Written in C# Targeting Dot Net Standard 2.0. There is also a sample app here, which is deployed to

#Using the Sample App


  • You will be directed to Yahoo! Auth Page, and asked to login (notice the url is Yahoo! meaning the app does not collect or track login information Login

  • After logging in and giving app read-only access to profile, you will be directed back to Home, with logged in status Login

Using this Wrapper

  • git clone
  • Reference project in solution

Per Microsoft, Dot Net Standard 2.0 supports development in Dot Net Core 2.0, .Net Framework 4.6.1, Mono 5.4, UWP vNext, and various versions of Xamarin.

Getting Api Access from Yahoo

  • Direct to Yahoo Apps Page
  • Fill Out Form as needed
  • Be sure set Callback to
  • Copy Client Id and Client Secret (note Callback Domain as well)

Dot Net Core 2.0 Example

  • Create Add Configuration Details from Yahoo in appsettings.json
  "YahooConfiguration": {
    "ClientSecret": "",
    "RedirectUri": "",
    "ClientId": ""
  • In Startup.cs ConfigureServices, configure instance of YahooConfiguration class to use throughout application
  • In Service you want to Inject Wrapper into, build controller
       private readonly IYahooAuthClient _client;
       private readonly IYahooFantasyClient _fantasy;

       public YahooService(IYahooAuthClient client, IYahooFantasyClient fantasyClient)
           _client = client;
           _fantasy = fantasyClient;

You are now ready to start the process of invoking OAuth Flow

Calling Yahoo Api

In order to call the Api (fantasy sports content), you need to obtain an Access Token from Yahoo using OAuth 2.0. Review the Yahoo OAuth 2.0 Guide for more information on this. To obtain an Access Token, we will leverage the YahooClient instance from the Wrapper. The steps are as follows

  • Get Url of Yahoo Auth Page _client.GetLoginLinkUri();
  • This will build a Uri with the Client Id, Client Secret, and Redirect Uri supplied eariler.
  • You will be brought to Yahoo Login and eventually App Access Authorization Page. Click Agree
  • Yahoo will validate your app, and redirect back to your Redirect Uri with added QS of ?code=authCode
  • Your callback uri will need to capture the request, collect the QS and validate the user and obtain a token
await _client.GetUserProfile(System.Web.HttpUtility.ParseQueryString(Request.QueryString.Value));
  • At this point, we have everthing we need to call the Yahoo Fantasy Sports Api.
//Get 2017 Football Leagues for Logged-In User
_fantasy.GetLeagues(new string[] { "371" }, EndpointSubResourcesCollection.BuildResourceList(EndpointSubResources.MetaData), _client.Auth.AccessToken)

The goal is to provide complete support of the Yahoo Api. For more information on the Api, reference the Doc on Yahoo

If you would like to contribute, let me know. I could use the help!



Copyright (c) 2017 Isaac Levin

Follow me online:

Twitter: @isaac2004


Wrapper for the Yahoo Fantasy Sports API. Includes Authorization and Data Retrieval







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