OnliKit

Merge JSON Files

Deep-merge objects or combine JSON files into one array in your browser

Use Merge JSON Files free in your browser. Free online JSON merger. Upload multiple JSON files, deep-merge nested objects with conflict highlights, or combine roots into one array — runs in your browser, no signup.

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What you can do with Merge JSON Files

Merge JSON Files on OnliKit is a free browser tool for everyday work — deep-merge objects or combine json files into one array in your browser. Use it when you need a quick result without installing software or creating an account.

  • Upload two or more .json files and reorder them before merging.
  • Deep-merge nested objects with later files winning on conflicts.
  • Choose Concat arrays or Last file wins for array fields during deep merge.
  • Switch to Combine as array to wrap each file’s root value in one JSON array.
  • See conflict paths and which file won before you download.
  • Copy or download merged.json — processing stays on your device.

Why use Merge JSON Files?

Use Merge JSON Files when you need one payload from several config fragments, locale packs, API fixtures, or environment overlays. Upload the files, set merge order, and preview the result before you commit or deploy.

Deep merge keeps a single object tree and surfaces overlapping keys so you can spot overrides. Combine as array is better when each file is a record or document you want listed side by side instead of folded together.

Everything runs locally in your browser. OnliKit does not upload your JSON to a server for this tool, so secrets in configs stay on your machine.

How to use Merge JSON Files

  1. 01Drop or browse to add at least two .json files.
  2. 02Reorder the list so later files override earlier ones where keys conflict.
  3. 03Choose Merge objects (optionally Concat arrays or Last file wins) or Combine as array.
  4. 04Review conflict highlights if shown, then copy or download merged.json.

Frequently asked questions

Can I merge multiple JSON files online for free?

Yes. Upload two or more JSON files, pick a merge mode, and download the result. No account is required.

Does merging JSON upload my files to a server?

No. Parsing and merging run entirely in your browser. Nothing is sent to OnliKit servers for this tool.

What is the difference between deep merge and combine as array?

Deep merge folds objects into one tree (later files override nested keys). Combine as array puts each file’s root value into a single JSON array in upload order.

How are conflicting keys handled?

In Merge objects mode, later files win. The conflict list shows paths that changed across files so you can confirm overrides before downloading.

What if my JSON files are arrays at the root?

Use Combine as array, or deep-merge only when every file’s root is a plain object. Root arrays are not deep-merged into a single object.

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