Question 1

How are nested objects and arrays represented as CSV columns?

Accepted Answer

Nested object keys are joined with a dot (address.city becomes a column named address.city), and array items are flattened by index the same way (tags.0, tags.1, tags.2). CSV has no concept of nesting, so this dot-notation flattening keeps every value in its own column rather than dumping a raw JSON blob into a cell.

Question 2

What happens if the objects in my array have different sets of keys?

Accepted Answer

The output columns are the union of every key seen across all rows, in the order first encountered. Rows missing a given key simply get an empty cell there — no error, no dropped rows — so a JSON array with inconsistent shapes (common with optional fields) still converts cleanly.

Question 3

Can I convert a single JSON object, not just an array of objects?

Accepted Answer

Yes — a single object converts to a one-row CSV (with its flattened keys as headers), and an array of objects converts to one row per array item. You do not need to wrap a single object in an array first.

Question 4

Will Excel or Google Sheets open the downloaded file correctly?

Accepted Answer

Yes — the file is written as standard UTF-8 CSV with comma separators and proper quoting for any value containing a comma, quote, or line break, which both Excel and Google Sheets read natively.

JSON to CSV

Smart Flattening

Handles Large Datasets

Local Processing

Frequently Asked Questions