How to Use the JSON Merge Tool

1

Prepare Your JSON Data

Paste one complete JSON object per line in the input area, or upload multiple JSON files using the file selector.

{"name": "John", "age": 30}
{"name": "Jane", "city": "NYC"}
2

Choose Merge Strategy

The tool automatically detects object vs array merging. Objects are deep-merged, arrays are concatenated.

  • Objects: Later properties overwrite earlier ones
  • Arrays: Arrays are combined in order
  • Mixed types: Combined into an array
3

Merge and Review

Click "Merge JSON" to combine your data. Review the merged result and any error messages.

4

Copy the Result

Use the "Copy Result" button to copy the merged JSON to your clipboard for use in your applications.

Use Case Examples

Configuration Merging

Merge multiple configuration files from different environments or sources into a single configuration object.

Input: 
{"database": {"host": "localhost"}}
{"database": {"port": 5432}, "debug": true}
Output: 
{"database": {"host": "localhost", "port": 5432}, "debug": true}

API Response Aggregation

Combine multiple API responses or paginated data into a single dataset for processing.

Arrays to merge: 
[{"id": 1, "name": "Item 1"}]
[{"id": 2, "name": "Item 2"}]

Data Migration

Merge data from multiple sources during migration or ETL processes, combining related records.

User profiles: 
{"user": {"id": 123, "basic": {"name": "John"}}}
{"user": {"id": 123, "details": {"email": "john@example.com"}}}

Frequently Asked Questions

How does the JSON merge work?

The tool performs deep merging for objects and concatenation for arrays. Later properties overwrite earlier ones in objects, while arrays are combined in order.

What happens with conflicting keys?

For objects, later keys overwrite earlier ones. For nested objects, the merge is performed recursively. Arrays are always concatenated rather than merged.

Is my data secure?

Yes! All merging happens locally in your browser. Your JSON data never leaves your device or gets transmitted to our servers, ensuring complete privacy.

Related Tools

After merging your JSON, use our JSON Validator to ensure the merged data is valid, or try the CSV ↔ JSON Converter to convert CSV data to JSON before merging.

JSON Merge Tool

Merge multiple JSON objects or files. 100% client-side. Secure, fast, and private.

Instructions:
  • Paste one complete JSON object or array per line in the input box, or upload one or more .json files using the 'Choose Files' button.
  • Each line/file must be valid JSON (not a fragment, no trailing commas, etc). Non-object/array values are skipped.
  • All JSON objects and arrays will be merged. For objects, later keys overwrite earlier ones. For arrays, arrays are concatenated by order.
  • Any invalid JSON or skipped value will be listed in messages below.
  • The merged result appears below, and can be copied with one click.
Paste or Upload JSON Objects/Files
Merged JSON Result