Firebase Realtime Database is a NoSQL cloud database that synchronizes data in real-time across clients using WebSockets, with offline support and simple JSON data structures.

Firebase Realtime Database is unstable in China - WebSocket connections frequently fail due to GFW interference and endpoint blocking. Developers require fallback to local WS proxies or switch to domestic real-time databases like Tencent TDSQL or LeanCloud Realtime.

The information regarding service availability in China is provided for general reference purposes only. Due to the dynamic nature of network conditions and regulatory environments, the actual accessibility of these services may vary over time and by location. Users are advised to verify the current status independently.