JSON Unflatten from Dot Notation
Rebuild a nested JSON object from a flat map of dot notation keys, which is the exact inverse of flattening and just as useful. Config systems, translation files and form data often arrive as a single level of dotted paths, and this tool expands them back into the real nested structure your code expects. It parses each key, splitting on dots and reading bracketed numbers as array indices, then creates the intermediate objects and arrays needed to place every value. Leaf values keep their original JSON type, so numbers and booleans are not turned into strings. Paste a flat JSON object whose keys are dotted paths, click unflatten, and copy the nested result. Everything runs locally in your browser, so the data you rebuild never leaves your device or gets logged elsewhere.
How to use JSON Unflatten
- Paste flat dot-notation JSON.
- Click unflatten to rebuild the structure.
- Copy the nested JSON.
Frequently asked questions
What input does unflatten expect?
It expects a flat map whose keys are dot-notation paths, and it rebuilds the nested object those paths describe.
How are array indices restored?
Bracketed numeric segments like items[0] are turned back into real array elements at the right positions.
Is it the inverse of flatten?
Yes. Unflatten reverses flatten, taking dot-notation keys back into a proper nested structure.
What is JSON Unflatten?
Rebuild a nested JSON object from a flat map of dot notation keys, which is the exact inverse of flattening and just as useful. Config systems, translation files and form data often arrive as a single level of dotted paths, and this tool expands them back into the real nested structure your code expects.
Is JSON Unflatten free to use?
Yes. JSON Unflatten is completely free, with no sign-up and no usage limits.
Does JSON Unflatten work in a web browser?
Yes. JSON Unflatten runs in any modern web browser. There is nothing to download or install.
Is my data private with JSON Unflatten?
Yes. JSON Unflatten runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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