Sync is a real-time state synchronization API designed for Twilio Programmable Voice, Video, IP Messaging, or other Twilio products, allowing developers to easily synchronize state across devices and between users. With Sync, developers can focus on building features instead of managing complex state synchronization infrastructure. The API provides three types of mutable JSON objects - Document, List, and Map - suitable for different use cases, including pub/sub, location data synchronization, and presence management. Sync is available as a developer preview, with initial access limited to a select number of developers who can request early access through the Twilio website.