JSON Flatten / Unflatten

Runs in browser JSON & Data

Convert deeply nested JSON to a single-level object with paths like user.address.city (and array indexes), or reverse a flat map back into a nested structure.

Privacy: This tool runs entirely in your browser. Your input never leaves your device.

How to use JSON Flatten / Unflatten

  1. Paste a nested JSON document (to flatten) or a flat key/value object (to unflatten).
  2. Pick the delimiter and array index style.
  3. Click Flatten or Unflatten and copy the output.

JSON Flatten / Unflatten features

  • Flattens nested objects and arrays into single-level path keys
  • Choice of delimiter (., /, _, __, :) and dot or bracket array indexes
  • Preserves empty objects and arrays
  • Unflattens path keys back into nested structures
  • Detects conflicting keys that cannot be nested
  • Statistics on key count and path depth

JSON Flatten / Unflatten example

Flatten a user record

Input:

{"user":{"name":"Layla","roles":["admin","editor"]},"active":true}

Output:

{
  "user.name": "Layla",
  "user.roles.0": "admin",
  "user.roles.1": "editor",
  "active": true
}

Frequently asked questions about JSON Flatten / Unflatten

What does flattening produce?

A single-level object whose keys are full paths, for example user.address.city or user.roles.0. Empty objects and arrays are preserved as {} and [] so no information is lost.

Can I get bracket-style array paths?

Yes — choose "Brackets" to output user.roles[0] instead of user.roles.0. Both styles are understood when unflattening.

When would I use a different delimiter?

Use "__" or ":" when your keys already contain dots (domain names, version numbers) so paths stay unambiguous, or "/" to mimic pointer-style keys.

Why does unflatten fail with a "conflict" error?

Two keys describe incompatible structures, e.g. "a": 1 and "a.b": 2 — "a" cannot be both a number and an object. Remove or rename one of them.