Flatten nested JSON to CSV
Paste or drop a JSON object or array. Get a flat CSV table with dotted column names. Runs in this tab. Nothing leaves it.
.json file here, or choose one. Max 1 MB.Input
One JSON document: an object or an array. Up to 1,048,576 bytes (1 MB). Paste it, or drop a file. UTF-8.
Output
RFC 4180 CSV with a header row. Nested objects become dotted column names (user.id). An array of objects becomes rows, and the header is the union of every key, sorted. Missing values are empty cells. Arrays of plain values are joined with | in one column. Booleans and numbers keep their JSON form. Nothing is silently dropped: a colliding path keeps its full name.
Limits
- One document per run. No merging across files.
- Nesting up to 64 levels, up to 10,000 columns, up to 200,000 rows. Past that the tool stops and says so.
- No schema inference, no type coercion, no account, no settings.
Nothing stored
The flattening runs in your browser tab. This page makes no network request with your data. There is no upload, no cookie, no local storage, no analytics of the payload. Close the tab and it is gone.
Errors
Every error names the field, the rule, and shows a small valid example. There is no support desk. If the box does not explain it, the input is outside what this tool does.