Authorization Code

This way is not recommended for client-side apps and requires server-side code to run securely. With this approach, you first get a code which you need to trade against the access-token. In this exchange you need to provide your Client-Secret and because of that it's not recommended. A good thing about this method: You can always refresh your token, without having the user to auth it again.

More info: here

static async void Main(string[] args){    AuthorizationCodeAuth auth = new AuthorizationCodeAuth(      _clientId,      _secretId,      "http://localhost:4002",      "http://localhost:4002",      Scope.PlaylistReadPrivate | Scope.PlaylistReadCollaborative    );
    auth.AuthReceived += async (sender, payload) =>    {        auth.Stop();        Token token = await auth.ExchangeCode(payload.Code);        SpotifyWebAPI api = new SpotifyWebAPI()        {          TokenType = token.TokenType,          AccessToken = token.AccessToken        };        // Do requests with API client    };    auth.Start(); // Starts an internal HTTP Server    auth.OpenBrowser();}

Token Refresh

Once the AccessToken is expired, you can use your RefreshToken to get a new one. In this procedure, no HTTP Server is needed in the background and a single HTTP Request is made.

// Auth code from above
if(token.IsExpired()){  Token newToken = await auth.RefreshToken(token.RefreshToken);  api.AccessToken = newToken.AccessToken  api.TokenType = newToken.TokenType}