Unflatten dot-notation JSON

Rebuild nested JSON objects and arrays from flat dot-notation keys.

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ToolJSON Unflatten
Input
Output
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Preview

How it works

Flat keys are split on the selected delimiter, numeric segments become array indexes, and each path is assigned into a new object or array. Later assignments can replace earlier values when paths collide.

  • Dot notation matches common flattened keys.
  • Numeric segments support indexed arrays.

Worked example

Dot Notation to Nested
Reconstruct nested objects from dot-notation keys
Input
											{"user.name": "Alice", "user.address.city": "Portland", "active": true}
Output
												{
  "user": {
    "name": "Alice",
    "address": {
      "city": "Portland"
    }
  },
  "active": true
}

When to use this

Form maps, CSV path columns, and query-string objects use unflattening.

Edge cases

  • A literal delimiter in a key becomes a path separator unless another delimiter is chosen.
  • Sparse indexes create empty positions between assigned elements.
  • Conflicting scalar and nested paths cannot both occupy the same location.

References