The Copilot API is a tool provided by Twilio that helps developers manage and optimize their SMS messaging system. It allows users to organize phone numbers into Messaging Services, configure settings such as sender IDs, and automate the selection of the best phone number to send from for each message. The API offers features like Geo-Match, Sticky Sender, Scaler, and Reroute, which help improve response rates, conversation history, and carrier compliance. With the Copilot API beta, developers can now access these features programmatically, making it easier to manage their SMS messaging system without requiring ongoing attention or engineering resources.