firebase – Database Rules – The default rules

The default rules require Authentication.
They allow full read and write access to authenticated users of your app. They are useful if you want data open to all users of your app but don’t want it open to the world.

// These rules require authentication
{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null"
  }
}

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firebase – Database Rules – The default rules - CodeDay