JSON Flatten / Unflatten
Flatten nested JSON into flat dot-notation pairs — or rebuild nested JSON from a flattened object.
How flattening works
Flatten walks the object tree and produces one key per leaf value, joining path segments with a
dot: {"user.address.city": "London"}. Array items are indexed numerically
(tags.0, tags.1). Unflatten reverses this: keys are split on dots and
segments that are numeric become array indices — so the round trip restores the original structure.
FAQ
When is this useful?
Flattened JSON is ideal for spreadsheets, databases with key-value storage, diffing two payloads, or configuration systems that only accept flat keys.
What if my keys contain dots?
A key like "a.b" will be treated as two path segments when unflattening. If your keys contain literal dots, the round trip may differ — use keys without dots for lossless results.
Is my data uploaded?
No. Everything runs in your browser.
JSON Flatten / Unflatten — FAQ
Is JSON Flatten / Unflatten free to use?
Yes. It is completely free, with no signup, no installation and no usage limits.
Is my data uploaded to a server?
No. The tool runs entirely in your browser — the data you paste or upload never leaves your device.
Does it work on mobile devices?
Yes. It works in any modern desktop or mobile browser, with nothing to install.