JSON Flattener
Flatten nested JSON into dotted keys or CSV columns, and turn flat data back into nested JSON.
Free, no uploads, no sign-up. Runs 100% in your browser.
How JSON Flattener works
Objects are walked key by key and each leaf gets a path like address.city or orders.0.sku. Lists can become one column per item, a joined text, or stay as JSON. Unflatten reverses it and restores numbers, true, false and null.
Input: JSON, CSV. Output: CSV, JSON.
How to use JSON Flattener
- Paste or open nested JSON.
- Pick the separator and how to treat arrays.
- Copy or download the CSV or flat JSON.
- Use Unflatten to go back.
Tips
- Nothing is uploaded. Your files stay in this browser tab.
JSON Flattener FAQ
- Are my files uploaded?
- No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
- Is it free? Are there limits or watermarks?
- Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
- Does it work offline?
- Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.
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