JSON to Firebase List — Free Online Firebase Realtime Database Converter

What Is Firebase Realtime Database?

Firebase Realtime Database (RTDB) is a cloud-hosted NoSQL database from Google that stores data as a JSON tree. Changes synchronize in real-time to all connected clients within milliseconds.

Key properties:

Firebase Realtime Database Structure

Data in RTDB is a JSON tree addressed by paths:

https://your-project.firebaseio.com/users/-Mabc123/name
                                 ↑ path   ↑ key    ↑ field

{
 "users": {
   "-Mabc123": {
     "name": "Alice",
     "age": 30,
     "active": true
   },
   "-Mdef456": {
     "name": "Bob",
     "age": 25,
     "active": false
   }
 }
}

Key Types in Firebase

Why Push Keys Are Recommended

Firebase push keys are auto-generated 20-character strings (e.g., -Mabc123xyz). They are:

• Chronologically ordered — newer keys sort after older ones

• Globally unique — no collisions across clients

• Collision-free for offline — generated without server round-trip

• Uniformly distributed — no hot-spotting in database sharding

Array indices (0, 1, 2) are discouraged because:

• Inserting or deleting items shifts all indices

• Concurrent modifications cause data loss

• Firebase documentation recommends against using array indices as keys

Why Convert JSON to Firebase Format?

Core Features

1. Dual Input Modes

• File Upload: Drag and drop or select a .json file.

• Code Editor: Paste or type raw JSON with syntax highlighting and real-time validation.

2. Path

Set the root path in the Firebase Realtime Database where data will be stored.

3. Key Type

Controls how each item in the JSON array is keyed in the Firebase output.

Push Key (Recommended)

Auto-generates unique Firebase-style push keys for each item.

Input:

[
   {"name": "Alice", "age": 30},
   {"name": "Bob", "age": 25}
]

Output:

{
   "-Mabc123xyz": {"name": "Alice", "age": 30},
   "-Mdef456uvw": {"name": "Bob", "age": 25}
}

Array Index

Uses numeric indices (0, 1, 2) as keys.

Output:

{
   "0": {"name": "Alice", "age": 30},
   "1": {"name": "Bob", "age": 25}
}

Not recommended for production — concurrent edits cause data loss.

Custom Key

Uses a specified field from each data object as the key.

Configuration: Custom Key Field = "email"

Input:

[
   {"email": "[email protected]", "name": "Alice"},
   {"email": "[email protected]", "name": "Bob"}
]

Output:

{
   "[email protected]": {"email": "[email protected]", "name": "Alice"},
   "[email protected]": {"email": "[email protected]", "name": "Bob"}
}

Custom key values must be strings and unique across all items.

4. Custom Key Field

Specifies which field from the JSON data to use as the Firebase key. Only applicable when Key Type is set to "Custom Key".

Common choices:

Important: Firebase keys must be strings and cannot contain ., #, $, /, [, or ].

5. Indent

Controls the output JSON formatting:

6. Output Options

Wrap with Path

Wraps the output in a root node matching the specified Path.

Enabled (path = users):

{
   "users": {
       "-Mabc123": {"name": "Alice"},
       "-Mdef456": {"name": "Bob"}
   }
}

Disabled:

{
   "-Mabc123": {"name": "Alice"},
   "-Mdef456": {"name": "Bob"}
}

Include Null Values

Controls whether fields with null values are kept in the output.

Enabled: {"name": "Alice", "phone": null}
Disabled: {"name": "Alice"} (phone field removed)

Firebase treats null as deletion — enabling this may cause fields to be deleted on import.

7. Privacy by Design

All processing runs entirely in your browser. No data is uploaded to any server.

How to Use This JSON to Firebase List Converter

Step 1: Provide Your JSON Data

Choose one of two input methods:

• Upload a file: Click "Choose File" and select a .json file, or drag it into the upload area.

• Paste data: Click "Enter Data" to switch to the code editor. Paste your JSON array.

Important: The tool expects a JSON array of objects.

Step 2: Configure Firebase Output

Use the Properties panel on the right:

1. Path: Enter the Firebase path (e.g., users, app/data/products).

2. Key Type: Choose Push Key (recommended), Array Index, or Custom Key.

3. Custom Key Field: If using Custom Key, specify the field name (e.g., email).

4. Indent: Choose output formatting.

5. Output Options: Enable Wrap with Path and/or Include Null Values.

Step 3: Convert

Click Convert. The Firebase-compatible JSON appears in the "Output Data" panel.

Step 4: Copy or Download

• Click Copy to Clipboard to paste into Firebase Console or save as .json.

• Premium users can click Download File to save.

Complete Example

Example — User List with Push Keys

Input JSON:

[
   {"name": "Alice", "email": "[email protected]", "role": "admin", "active": true},
   {"name": "Bob", "email": "[email protected]", "role": "editor", "active": true},
   {"name": "Charlie", "email": "[email protected]", "role": "viewer", "active": false}
]

Configuration:

• Path: users

• Key Type: Push Key

• Indent: 2 Spaces

• Wrap with Path: On

• Include Null Values: Off

Output:

{
 "users": {
       "-Mabc123xyz": {
     "name": "Alice",
     "email": "[email protected]",
     "role": "admin",
     "active": true
   },
   "-Mdef456uvw": {
     "name": "Bob",
     "email": "[email protected]",
     "role": "editor",
     "active": true
   },
   "-Mghi789rst": {
     "name": "Charlie",
     "email": "[email protected]",
     "role": "viewer",
     "active": false
   }
 }
}

Example — Product Catalog with Custom Keys

Input JSON:

[
   {"sku": "LAPTOP-001", "name": "Pro Laptop", "price": 1299.99, "stock": 45},
   {"sku": "PHONE-001", "name": "Smart Phone", "price": 699.99, "stock": 120},
   {"sku": "TABLET-001", "name": "Air Tablet", "price": 499.99, "stock": 0}
]

Configuration:

• Path: products

• Key Type: Custom Key

• Custom Key Field: sku

• Wrap with Path: On

Output:

{
 "products": {
   "LAPTOP-001": {
     "sku": "LAPTOP-001",
     "name": "Pro Laptop",
     "price": 1299.99,
     "stock": 45
   },
   "PHONE-001": {
     "sku": "PHONE-001",
     "name": "Smart Phone",
     "price": 699.99,
     "stock": 120
   },
   "TABLET-001": {
     "sku": "TABLET-001",
     "name": "Air Tablet",
     "price": 499.99,
     "stock": 0
   }
 }
}

Example — Flat List (No Path)

Configuration:

• Path: (empty)

• Key Type: Push Key

• Wrap with Path: Off

Output:

{
 "-Mabc123": {"name": "Alice", "active": true},
 "-Mdef456": {"name": "Bob", "active": false}
}

Firebase Key Restrictions

Firebase Realtime Database keys have restrictions that differ from regular JSON:

Firebase RTDB vs. Firestore

This tool generates data for Realtime Database specifically.

Frequently Asked Questions (FAQ)

• Does the tool upload my data to Firebase?

  No. All conversion happens locally in your browser using JavaScript. The tool only transforms the JSON format — you import the result into Firebase yourself.

• What is a Firebase push key?

  A push key is a unique, auto-generated identifier created by Firebase (e.g., -Mabc123xyz). It is chronologically ordered, globally unique, and collision-free — making it ideal for lists in Realtime Database.

• Should I use Push Key, Array Index, or Custom Key?

  Use Push Key for new records without a natural identifier (most cases). Use Custom Key when you have a unique natural key like email, SKU, or slug. Avoid Array Index for production data — concurrent edits cause data loss.

• How do I import the output into Firebase?

  Use the Firebase Console (Import JSON button), Firebase CLI (firebase database:set), or the REST API (PUT or PATCH to your database URL). See the Import section above for details.

• What characters are not allowed in Firebase keys?

  Firebase keys cannot contain ., #, $, /, [, ], or ASCII control characters.

• What does "Wrap with Path" do?

  It wraps the output in a root node matching the Path you specified. Without it, the output is the raw keyed list without a path wrapper.

• What does "Include Null Values" do?

  When enabled, fields with null values are kept in the output. When disabled, they are removed. Note: importing null values into Firebase deletes those fields.

• Can I use this for Firestore?

  No. This tool generates data for Firebase Realtime Database. Firestore uses a different document/collection model.

• Is there a file size limit?

  The tool processes data entirely in your browser. Files up to 10 MB typically convert without issues. Firebase RTDB limits individual node values to 10 MB.

• Can I use this on mobile?

  Yes. The tool is responsive and works on smartphones and tablets.