Flattening a nested address
{ "user": { "address": { "city": "London" } } }{ "user.address.city": "London" }JSON Flatten / Unflatten
Flatten nested JSON to dot/bracket-path keys, or rebuild the nested structure from flat keys.
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About this tool
A deeply nested JSON document doesn't fit a spreadsheet column, an env variable, or a form field particularly well — flattening it to `parent.child[0].grandchild`-style keys does. Unflattening reverses the same operation, for whichever direction the day's task needs.
How to use it
- Flatten mode: paste a nested JSON value, get back a flat object of dot/bracket-path keys.
- Unflatten mode: paste a flat object of such keys, get back the reconstructed nested structure.
Examples
Common problems
- Unflatten fails on a document that isn't a plain object.
- Unflatten expects a flat object as input (the direct output of Flatten mode) — a JSON array or a primitive value at the top level has no keys to rebuild from.