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# Flatten and unflatten JSON

Collapse nested objects into dot-separated keys, or rebuild the tree from flat keys. Separator characters are escaped inside keys, collisions are caught before any output, and ambiguous unflatten input is refused with the key named.
FlattenUnflattenSeparatora[0]a.0keep arraysCopyDownloadNothing in yet

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nested in, flat keys out: and back

## Next door in JSON

- [JSON formatter](/json/formatter)
- [JSON Query](/json/query)
- [JSONL / NDJSON](/json/jsonl)
[All JSON tools](/json)

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Canonical HTML: https://nutter.tools/json/flatten
Markdown version: https://nutter.tools/json/flatten/index.md
Plain-text version: https://nutter.tools/json/flatten/index.txt
Agent index: https://nutter.tools/llms.txt