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JSON Merge | Combine Arrays and Objects, Remove Duplicates

Safely merge multiple JSON files in your browser. Concatenate arrays, merge object keys or shared arrays, remove duplicates, and review key conflicts.

Data/Utility

Select up to 50 JSON files (20 MB total). Files are processed only in this browser.

0Uploaded files
-Merged item count
-Duplicate keys (object mode)
-Output size (bytes)

Upload multiple JSON files with similar format and merge/download them at once.

Download merged.json

When should you use JSON Merge?

Use it when split JSON files with similar schema need to be combined quickly.

Examples: paged API exports, chunked logs, and batch output files.

Key features

  • Multi-file JSON upload
  • Auto mode detects array/object structure
  • Manual modes: array concat, object key merge, wrap roots into array
  • Preview + merged.json download
  • Optional array deduplication + object key conflict count
  • Clear errors for invalid JSON, incompatible manual modes, and excessive file size

How to use

  1. Upload multiple JSON files.
  2. Pick a merge mode (default: Auto).
  3. Click Merge JSON.
  4. Review and download the result.

Notes

  • In object-merge mode, duplicate keys are overwritten by later files.
  • Manual object-merge mode requires every file root to be a JSON object. Incompatible structures are rejected with an error.
  • To protect browser memory, each run accepts up to 50 files with a combined size of 20 MB.
  • Uploaded files and merged results stay in your current browser and are never sent to a server.

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