Flatten Nested JSON Online (and Unflatten)
Flatten nested JSON to dot-notation keys or unflatten back to nested — arrays use index paths. Free, instant, 100% in your browser.
Input · json0 chars
Output · json0 chars
🔒 100% private: this tool runs entirely in your browser. Your data is never uploaded, stored or logged anywhere.
How to flatten json
- Paste nested JSON and press nothing — output is instant.
- Switch to Unflatten mode to rebuild nested structure from dot keys.
- Copy or download the result.
FAQ
How are arrays flattened?
Array elements become index paths: tags.0, tags.1, … Unflatten reconstructs them as arrays only when keys are numeric — otherwise plain objects.
What about empty objects?
Empty objects become a key with {} value; unflatten restores them as empty objects.
Why flatten JSON at all?
Flattened rows feed perfectly into CSV/spreadsheets, search indexing, and analytics pipelines that expect flat records.