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Merge JSON

Combine JSON documents with live conflict previews, deep or shallow merging, and explicit array rules.

Source
97 / 1,000,000 charactersLocal only
Source
80 / 1,000,000 charactersLocal only

Matching objects merge recursively. Arrays are replaced by incoming arrays. Null stays null.

1Added paths
2Changed paths
0Removed paths
Merge preview
Merged JSON preview
{
  "theme": {
    "mode": "dark",
    "accent": "blue"
  },
  "plugins": [
    "export"
  ],
  "autosave": true,
  "welcome": "Hello"
}
Processed on your device

How it works & useful details

How it works

Incoming values win conflicts. Deep mode merges matching objects recursively and uses your array policy; shallow mode replaces matching values as a whole. A root array follows the array policy. Concatenation preserves order and duplicates. Null is an ordinary value, not deletion. This is a configurable merge, not RFC7396 Merge Patch.

Limits & privacy

Up to 1,000,000 characters, 50,000 values and 64 levels. Live previews pause above 40,000 characters; run the tool to process the full supported input. Imported files must be UTF-8 and under 1 MB. Your data stays on this device.

Numbers use JavaScript decimal precision. Unsupported large integers are rejected; quote identifiers to keep all digits. Duplicate object names keep their last value. Transforms preserve data, not source whitespace or number spelling.

Paths use JSON Pointer: an empty path selects the root, ~0 escapes a tilde, and ~1 escapes a slash.