BYTETOOLS

JSON Merge Tool

Deep merge two or more JSON files online. Choose who wins conflicts, replace, concatenate or union arrays, and see every conflicting path resolved.

What is the JSON Merge Tool?

The ByteTools JSON Merge Tool deep-merges two or more JSON documents into one. Objects are combined key by key at every depth, and when the same key holds different values you decide the outcome: later document wins or earlier document wins.

  • Deep recursive merge of any number of nesting levels
  • Later-wins or earlier-wins conflict strategy
  • Arrays: replace, concatenate, or union with deduplication
  • Reports every conflicting path and how it was resolved
  • Merge up to five documents in one pass
  • 100% private — files never leave your browser

How to use the JSON Merge Tool

  1. 1

    Paste your base JSON into Document 1 and the overriding JSON into Document 2.

  2. 2

    Add more documents if needed (up to five, merged in order).

  3. 3

    Choose the conflict strategy and how arrays should combine.

  4. 4

    Click Merge, review the resolved conflicts, then copy or download the result.

About the JSON Merge Tool

The ByteTools JSON Merge Tool deep-merges two or more JSON documents into one. Objects are combined key by key at every depth, and when the same key holds different values you decide the outcome: later document wins or earlier document wins. Arrays get their own strategy — replace, concatenate, or union with duplicates removed.

It is ideal for combining configuration files, layering environment overrides onto a base config, or consolidating exported data. After merging, the tool lists every conflicting path it resolved — like $.server.port — so you can audit exactly which values were overridden instead of guessing.

Merging runs 100% locally in your browser with JavaScript. Your documents are never uploaded or stored, so private configuration files and API data are safe to combine here.

Frequently asked questions

How do I merge two JSON files into one?

Paste one document into each box, pick a conflict strategy and click Merge. Matching objects are combined recursively, and the merged JSON appears below with a list of every path where a conflicting value had to be resolved.

What happens when both files have the same key?

If both values are objects they are merged recursively. Otherwise the strategy decides: 'later document wins' takes the value from the later file, 'earlier document wins' keeps the first one. Every such decision is reported by path.

How are arrays merged?

You choose: replace keeps only the winning document's array, concatenate appends them in order, and union concatenates then removes exact duplicates. Arrays are never merged element-by-element, which avoids surprising pairings.

Can I merge more than two documents?

Yes — up to five. They merge left to right, so Document 1 is the base and each later document layers on top, which matches how config overrides usually work.

Is my data uploaded anywhere?

No. The merge is computed entirely in your browser. Nothing is transmitted or stored, so it is safe for secrets-adjacent configuration files.

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