How do you convert JSON records into CSV columns?

Question

Sheet Reserve · Accepted Answer

Use a JSON array of flat objects, collect the property names as column headers, and write each object’s values in that order. Missing properties become empty cells. Sheet Reserve’s converter uses every property name encountered across the records and runs locally. Flatten nested objects first, and represent long or leading-zero identifiers as strings in the original JSON.

For [{"id":"001","amount":12.5},{"id":"002","note":"paid"}], columns are id, amount, and note. The second record has a blank amount, and the first has a blank note.
What information can JSON to CSV conversion lose?
CSV has no native null, number, or object types. This tool writes both null and missing properties as empty fields. A nested object is rejected rather than silently reduced to an unhelpful text label.