Data

JSON Flatten & Unflatten

Normalize nested payloads for CSVs and form maps. Processing stays on your device — no upload, no account.

How to use JSON Flatten & Unflatten

  1. Paste nested JSON to flatten, or flat dotted keys to unflatten.
  2. Choose mode.
  3. Copy the result.

Why use this free flatten json tool?

  • All processing happens locally in your browser. Your files are never uploaded to a server.
  • Dotted-path keys.
  • Array index paths.
  • Bidirectional.

Technical details

Flatten walks objects/arrays; unflatten rebuilds trees from "a.b.0.c" style keys.

JSON Flatten & Unflatten FAQ

Uploaded?

No. All processing happens locally in your browser. Your files are never uploaded to a server.

Key collisions?

Later keys overwrite earlier ones when unflattening duplicates.

Prototype keys?

Avoid "__proto__" style keys — treat untrusted JSON carefully.

Empty objects?

Supported; empty arrays flatten to no child paths.

Related free converters

More private browser tools people use with flatten json.