# JSON Flattener

> Flatten deeply nested JSON into dot-notation keys, or expand flat keys back into nested objects.

To flatten JSON, paste a nested object and every leaf value is rewritten with a dot-notation path key such as user.address.city. This makes deeply nested API responses easy to diff, search, load into a spreadsheet or feed into a translation file.

**URL:** https://convertto.tech/t/json-flattener
**Category:** Data & Format Tools (https://convertto.tech/c/data-tools)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Enter or paste your json.
2. Choose the key separator.
3. Turn "Index into arrays" on or off as needed.
4. The result appears immediately — copy or download it.

## FAQ

### What is flattening for?

Getting nested JSON into anything that expects a flat table — a CSV, a spreadsheet, a database column set. A nested address object becomes address.city and address.postcode, which a table can hold and a nested object cannot.

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