I’d not used Google’s Domain-wide Delegation from Golang and struggled to find example code. Google provides Java and Python samples. Google has a myriad packages implementing its OAuth security and it’s always daunting trying to determine which one to use. As it happens, I backed into the solution through client.Options ctx := context.Background() // Google Workspace APIS don't use IAM do use OAuth scopes // Scopes used here must be reflected in the scopes on the // Google Workspace Domain-wide Delegate client scopes := []string{ .