Why are some columns empty?

The header row is the union of every key across all records. Any object missing a key gets an empty cell for that column — which is correct, but it is also a good signal that your records are not uniformly shaped.

What happens to nested arrays?

They are written as JSON text inside a single cell, because CSV has no way to express repetition inside a field. Switch the nested-value mode to keep objects as JSON too, rather than flattening them.

JSON to CSV

Flatten an array of objects into a spreadsheet-friendly table.

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About this tool

Collects the union of all keys across every row so that sparse records still line up in the right columns. Nested values can be flattened to dot notation or kept as embedded JSON.

Limitations

CSV is flat and JSON is not. Deeply nested structures always lose something in translation.
A top-level object is treated as a single row.

Questions

Why are some columns empty?: The header row is the union of every key across all records. Any object missing a key gets an empty cell for that column — which is correct, but it is also a good signal that your records are not uniformly shaped.
What happens to nested arrays?: They are written as JSON text inside a single cell, because CSV has no way to express repetition inside a field. Switch the nested-value mode to keep objects as JSON too, rather than flattening them.

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