Flatten JSON Online – Unflatten Nested Paths | JsonToTable

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JSON Input

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Client-side only · flatten tree

Flattened JSON

Flattened paths will appear here

Paste a nested object or array on the left. Arrays become [0], [1], … path segments.

A small order with a customer object, two line items, and a null note

Flattening and unflattening run in this browser tab only. Your JSON is not sent to our servers, and there is no cloud store for the trees you paste.

How to Flatten or Unflatten JSON

Use this page to flatten JSON into path keys, or unflatten a path object back into a tree. Switch the mode above the editors and copy pretty-printed JSON — a lossless walk of the tree, not a spreadsheet.

1

Step 1 – Paste a Nested Tree or a Path Object

For flatten mode, paste an object or an array. For unflatten mode, paste the single-level object this tool (or a compatible path syntax) produced. To inspect structure without rewriting it, use the JSON viewer.

🌳

Flatten - Walk every leaf and emit a path key.

↩

Unflatten - Rebuild the tree from those path keys.

Sample nested JSON

{
  "order": {
    "id": "ORD-1042",
    "customer": {
      "name": "Lina Ortiz",
      "vip": true
    },
    "items": [
      { "sku": "mug", "qty": 2 },
      { "sku": "coaster", "qty": 4 }
    ],
    "notes": null
  }
}

2

Step 2 – Read the Path Keys

Ordinary names are joined with dots (order.customer.name). Array members use brackets (items[0].sku). Keys that contain dots, spaces, or other punctuation are JSON-quoted inside brackets so they cannot be confused with a nested walk.

•

Dot paths - Safe identifiers stay unquoted.

[]

Brackets - Numeric indices and quoted unusual keys.

Flattened path object

{
  "order.id": "ORD-1042",
  "order.customer.name": "Lina Ortiz",
  "order.customer.vip": true,
  "order.items[0].sku": "mug",
  "order.items[0].qty": 2,
  "order.items[1].sku": "coaster",
  "order.items[1].qty": 4,
  "order.notes": null
}

3

Step 3 – Copy, or Unflatten to Verify the Round-Trip

Copy or download the pretty-printed result. Switch to Unflatten and paste the path object to rebuild the original tree. If what you actually need is a worksheet of columns, that is a different job — use JSON to Excel or JSON to CSV.

📎

Clipboard - Copies the pretty-printed JSON.

🔒

Local only - The tree never leaves this tab.

⚡Export the flattened or rebuilt JSON

2 Actions

📎

Clipboard

Copy pretty JSON

↩

Unflatten

Rebuild the original tree

💡Tip: unflatten(flatten(x)) matches x for objects, arrays, nulls, and quoted unusual keys.

Path Syntax Used by This JSON Flattener

When you flatten JSON, every leaf of the tree becomes one key. The spelling is chosen so unflatten can invert it.

Example path → meaning

Path	Meaning
`order.customer.name`	Plain identifiers joined with dots
`items[0].sku`	The first element of the items array
`[0].id`	A root-level array: first element’s id
`["a.b"]`	An object key that literally contains a dot
`["first name"]`	A key with a space, JSON-quoted inside brackets

Flatten JSON FAQs

Questions about path syntax, quoted keys, round-trip unflatten, and how this differs from a spreadsheet export

How do I flatten JSON online?

Paste a JSON object or array into the left editor, keep the mode on Flatten, and read the pretty-printed single-level object on the right. Each leaf becomes a path key such as order.customer.name or items[0].sku.

Can I unflatten the result back to the original tree?

Yes. Switch the mode to Unflatten and paste the path object. For ordinary objects, arrays, nested mixes, nulls, and quoted unusual keys, unflatten(flatten(x)) matches the original value.

How are unusual keys written?

Keys that are not plain identifiers (for example a key with a dot or a space) are JSON-quoted inside brackets, like ["a.b"] or ["first name"]. That spelling keeps unflatten unambiguous so a dotted key is never treated as a nested walk.

What happens with an empty array at the root?

A documented limit: both an empty root array and an empty root object flatten to {}. Unflatten therefore returns {}. Empty arrays nested under a parent key are preserved as [] and do round-trip.

Is this the same as exporting JSON to a spreadsheet?

No. This page only rewrites the JSON tree into path keys (and back). Flattening to a spreadsheet is a different job — use JSON to Excel or JSON to CSV when you need columns and rows instead of a path object.

Why did unflatten say two paths collide?

One path asked for an array at a location where another path already placed an object (or the other way around), for example a.b and a[0]. Fix the keys so every prefix agrees on the container type.

Does pasting upload my JSON?

No. Both flatten and unflatten execute locally in the page. The input never goes to an API on this site, and we do not keep a copy after you close the tab.

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