JSON Unflattener

The JSON Unflattener is the inverse of flattening: it reads an object of dot-notation keys and reconstructs the full nested structure they describe. Numeric path segments are rebuilt as arrays, and everything else becomes nested objects. It is the fastest way to turn a flat config map or spreadsheet export back into structured JSON.

• Rebuilds deeply nested objects from dotted key paths
• Reconstructs arrays from numeric path segments like items.0.sku
• Supports custom delimiters to match how the data was flattened
• Preserves the original type of every leaf value
• Detects conflicting paths and reports them clearly
• Round-trips with the JSON Flattener to restore the exact structure

1. 1

   Paste flat JSON

   Provide an object whose keys are dot-notation paths, such as user.address.city.

2. 2

   Match the delimiter

   Set the same separator that was used when the data was flattened.

3. 3

   Unflatten

   The tool expands the flat keys into a fully nested object and array structure.

4. 4

   Copy the nested JSON

   Use the reconstructed document in your app, API, or config.

• Restoring structured JSON from a spreadsheet exported as flat columns
• Turning flat environment-style keys back into a config object
• Rebuilding nested payloads from a key-value store
• Reassembling translation files stored as dotted paths
• Completing a flatten-edit-unflatten workflow on nested data