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Convert JSON to CSV

API responses and exports arrive as JSON; the person who needs to read them wants a spreadsheet. This takes a JSON array — or newline-delimited JSON — and produces a CSV, flattening nested objects into dotted column names so nothing is silently dropped.

How to use it

  1. Choose your .json or .ndjson file.
  2. Pick a delimiter if you need something other than a comma.
  3. Click Convert and download the CSV.

Questions

Is my file uploaded anywhere?

No. This page contains the whole tool — the JavaScript that does the work runs inside your browser tab, on your own machine. There is no server to upload to. You can confirm it yourself: open your browser's developer tools, switch to the Network tab, and run the tool. You will not see your file go anywhere. You can also disconnect from the internet after the page loads and it will still work.

How are nested objects handled?

They're flattened into dotted column names, so {"user": {"name": "Ann"}} becomes a column called user.name. Arrays are rendered as JSON text inside the cell, since there's no lossless way to spread them across columns.

What if my objects have different keys?

The header is the union of every key found across all objects. Rows missing a key get an empty cell rather than being skipped.