JSON to CSV Converter - Flatten Nested Data

JSON to CSV - handling the hard parts

Converting a flat JSON array of simple objects to CSV is trivial - each key becomes a column, each object becomes a row. The hard part is everything else: nested objects, arrays, inconsistent fields across objects, and special characters that need escaping. This is where most free converters fall apart.

Flattening nested objects

Consider this JSON:

{"name": "Rahul", "address": {"city": "Delhi", "zip": "110001"}}

CSV has no concept of nesting - every cell is a flat value. The standard approach is to flatten nested keys using dot notation, turning the address object into two columns: address.city and address.zip. This tool does this automatically and lets you toggle it off if you'd rather see nested objects as raw JSON strings in a single cell.

Handling arrays

Arrays present a choice. A simple array of strings like "tags": ["new", "sale"] can be joined into one cell as new; sale. But an array of objects - like a list of order items - doesn't fit neatly into one cell. This tool flattens array-of-object fields into indexed columns: items.0.name, items.0.price, items.1.name, and so on, up to the maximum array length found across all objects.

Inconsistent fields across objects

Real-world JSON often has objects with different shapes - some have an email field, others don't; some have extra metadata. This tool scans every object in your array, builds a union of all fields found, and fills in empty cells for objects missing a particular field. The column mapper shows you this full union before you export, so nothing is silently dropped.