JSON ↔ CSV Converter

Common Conversion Scenarios

[
  {"id": 1, "name": "Product A", "price": 29.99},
  {"id": 2, "name": "Product B", "price": 39.99}
]

id,name,price
1,Product A,29.99
2,Product B,39.99

{
  "user": {
    "name": "John",
    "address": {
      "city": "New York"
    }
  }
}

"123" → 123 (number)
"true" → true (boolean)
"2024-01-01" → date handling

Flattening Nested JSON for CSV

CSV is a flat, two-dimensional grid: rows and columns, with no concept of a nested object. JSON, by contrast, routinely nests objects inside objects. To bridge the two, this converter flattens nested objects using dot notation. A field like {"user": {"address": {"city": "New York"}}} becomes a single column headed user.address.city. Because each record may contain different keys, the converter scans every object, collects the full union of flattened keys, sorts them, and uses that as the header row, so records missing a particular field simply leave that cell empty rather than shifting columns out of alignment.

Arrays are handled differently from objects. Rather than exploding an array across many columns, the converter joins array values into a single cell separated by ;. So "tags": ["a", "b"] becomes one column containing a; b. This keeps the table readable, but it does mean deeply structured arrays of objects lose some fidelity. If you need every nested record as its own row, restructure the JSON into a flat array of objects first.

Delimiter, Quoting, and Escaping Pitfalls

The single most common cause of a mangled CSV is a value that itself contains the delimiter. If a product name is "Chair, Oak" and your delimiter is a comma, a naive converter would split it into two columns. Following RFC 4180, this tool automatically wraps any value containing the delimiter, a double quote, or a line break in double quotes, and it escapes embedded quotes by doubling them (" becomes ""). When reading CSV back into JSON, the parser respects those quotes so a quoted comma stays inside one field.

A few practical tips: if your data contains commas, switch to a semicolon or tab delimiter to keep the raw output easier to inspect. European spreadsheets often default to semicolons, so choose the delimiter your target program expects. When converting CSV to JSON, enabling auto-detect data types turns "123" into a number and "true" into a boolean. That is convenient, but disable it if you have identifiers like ZIP codes or phone numbers that must keep leading zeros and stay as strings.

Frequently Asked Questions