Firebase Realtime Database

The Firebase Realtime Database is a cloud-hosted NoSQL database that stores data as a single JSON tree and synchronises it in real-time across all connected clients. It is one of the original Firebase products and remains relevant for specific use cases where extreme low-latency synchronisation is required.

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What Is the Realtime Database?

The Firebase Realtime Database (RTDB) is a cloud-hosted JSON database that:

• Synchronises data in real-time across all connected clients within milliseconds.
• Works offline — data is cached locally and synced when connectivity returns.
• Uses a single JSON tree — all data is stored as one large JSON document.
• Scales for concurrent connections — designed for many simultaneous connected clients.

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Data Model

JSON Tree

All data is stored as a single JSON tree. Every piece of data is a node in the tree, identified by a path:

{
  "chat": {
    "room-001": {
      "messages": {
        "msg-001": {
          "sender": "alice",
          "text": "Hello!",
          "timestamp": 1705312200000
        },
        "msg-002": {
          "sender": "bob",
          "text": "Hi Alice!",
          "timestamp": 1705312260000
        }
      },
      "members": {
        "alice": true,
        "bob": true
      }
    }
  }
}

Accessing Data by Path