What is the difference between deep merge and shallow merge?

A shallow merge only combines the top-level keys of two objects. If both objects have the same key, the value from the second (right) object overwrites the first. A deep merge recursively merges nested objects, so sub-keys from both sides are combined rather than overwritten.

How are array conflicts handled?

You can choose from three array strategies: Concatenate (combines both arrays), Replace (uses the right object's array), or Merge by Index (combines element by element, preferring the right object's values for matching indices).

Is my JSON data sent to a server?

No — JSON Merger runs 100% in your browser. Your data never leaves your device. No uploads, no accounts, no tracking beyond anonymous analytics.

Can I merge more than two JSON objects?

The tool currently merges exactly two JSON objects at a time. To merge three or more, merge the first two, then paste the result into the left panel and add your third object to the right panel.

Does the tool handle JSON arrays at the root level?

Yes. If both inputs are root-level JSON arrays, the tool treats them as arrays and applies your chosen array merge strategy (concatenate, replace, or merge by index).

100% Free & Browser-Only

Merge Two JSON Objects
Instantly Online

Combine JSON objects with deep merge, shallow merge, or custom conflict resolution. No uploads. No account. Works entirely in your browser.

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Deep & Shallow Merge

Choose deep merge to recursively combine nested objects, or shallow merge to overwrite top-level keys only.

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Smart Array Handling

Control how arrays are merged — concatenate them, replace with the second value, or merge by index.

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Conflict Resolution

Decide how key conflicts are resolved: prefer the left object, the right object, or see both values.

Merge mode:

Arrays:

Conflicts:

LLeft JSON

RRight JSON

Frequently Asked Questions

Everything you need to know about JSON Merger.

Merge Two JSON ObjectsInstantly Online

Deep & Shallow Merge

Smart Array Handling

Conflict Resolution

Frequently Asked Questions

Merge Two JSON Objects
Instantly Online