JSON Flatten / Unflatten

JSON Flatten turns nested JSON into a single level of path keys — {"user": {"address": {"city": "Chennai"}}} becomes {"user.address.city": "Chennai"} — which is what spreadsheets, environment variables, translation files and many config systems expect. Unflatten does the reverse and rebuilds the nesting, including arrays. Choose the separator (. / _ or __) and whether array positions are written as items[0] or items.0. Keys that would be ambiguous are quoted so the round trip is exact, and empty objects and arrays are kept. An array of records can also be saved as a CSV with one row per record and one column per path.