The Real-time Bidding API is the replacement for the Ad Exchange Buyer API, and we encourage you to migrate before the sunset date in order to avoid interruptions to your integration. To learn more about the Real-time Bidding API, you can read the migration guide, reference documentation, and the new resource guides. Additionally, samples for several programming languages are available to assist you with your migrations.
If you encounter any issues, or have any questions we can assist with, please contact us via our support forums.