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JSON Flattener

Flatten nested JSON into one level of dotted or bracketed keys, including array indexes.

Flatten nested JSON

Flattened: —
Arrays become indexed keys in bracket mode or numbered keys in dot mode, and empty objects or arrays are kept as values.

How to use the JSON Flattener

  1. Paste the nested JSON you want to flatten.
  2. Choose dot notation or bracket notation for the keys.
  3. Press Flatten and copy the single level result.

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Frequently Asked Questions

Common questions about the free online json flattener.

Paste nested JSON, choose dot or bracket keys and press Flatten to get one level of key value pairs.
Dot notation writes user.address.city, while bracket notation writes user[address][city] for the same path.
Each array item gets an index in its key, so roles[0] and roles[1] hold the two values.
Empty containers cannot be split further, so they are kept as a whole value on their own key.
Yes. Null values are written as null on their flattened key, so no information is lost.
Yes. The flattened keys make good column headers, which is why this format is common in analytics imports.
No. Flattening runs entirely in your browser and the document you paste never leaves your device.
Yes. Nesting depth is limited only by the memory of your browser tab, and paths simply grow longer.
Yes. The flattener is completely free with no account, no limits and no sign-up.

Last updated: October 10, 2026