How many documents can I merge?

Add as many document panels as you need with the Add document button; they merge left to right.

What's the difference between shallow and deep merge?

Shallow merge only combines top-level keys; deep merge recursively merges nested objects.

How are array conflicts handled?

Choose concat to combine, replace so the later document wins, or union to combine while removing duplicates.

Is my data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your input never leaves your device and nothing is logged or stored on our servers.

Does it work offline and on mobile?

Yes. Once the page has loaded it keeps working without a network connection, and the layout is responsive so it stays usable on phones and tablets.

JSON Merger

Merge two or more JSON documents with shallow/deep strategies.

Support

Works Offline

Privacy First

No Login

No API

Object merge strategy

Array strategy

Document 1

Document 2

Merged result

JSON

{
  "name": "Grace",
  "skills": [
    "logic",
    "math"
  ],
  "meta": {
    "role": "admin",
    "active": true
  }
}

Conflicts (1)

name: "Ada" → "Grace"

About the JSON Merger

Combine multiple JSON documents using shallow or deep merge strategies, with configurable array handling (concat, replace, or union), and a report of every key conflict encountered.

Examples

Deep merge two objects

{"a":{"x":1}}
{"a":{"y":2}}

Output

JSON{"a":{"x":1,"y":2}}

Keyboard shortcuts

Copy the main outputCtrl / ⌘ + Shift + C
Download the resultCtrl / ⌘ + S
Share this toolCtrl / ⌘ + Shift + S
Reset the inputsAlt + R
Open the tool search paletteCtrl / ⌘ + K

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Frequently asked questions

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Version 1.0.0 · Updated 2026-08-10 · Runs entirely in your browser