CSV to JSON Converter

How This Tool Converts CSV to JSON

• The first row of your CSV is treated as the header row. Its column names become the keys for every JSON object in the output array. Untick First row is a header if your data starts straight at the first record.
• Each subsequent data row becomes one JSON object. Column order is preserved and each value is mapped to the header key of its column.
• The delimiter is detected from the header row — comma, semicolon, tab or pipe — by counting each candidate outside quoted regions. You can also pick one explicitly or type a custom character.
• Fields wrapped in double quotes are parsed correctly, including values containing the delimiter, escaped double quotes ("" → a literal ") and real line breaks. The parser reads the file as one character stream and tracks quote state across newlines, exactly as RFC 4180 requires.
• With Detect numbers & booleans on, 42 becomes the number 42 and true becomes a boolean. Values that would not survive the trip — leading zeros like 007, integers beyond Number.MAX_SAFE_INTEGER, and +-prefixed values — are deliberately kept as strings.
• Empty cells stay as empty strings ("") unless Empty cells as null is ticked.

Worked example

This CSV packs in every case that trips up naive parsers at once: an embedded comma, escaped quotes, a real line break inside a quoted field, a leading-zero code, a boolean and an empty trailing cell.

Input CSV

name,age,zip,active,note
Alice,30,007,true,"Likes ""tea"", coffee
and long walks"
Bob,25,90210,false,

Output JSON

[
  {
    "name": "Alice",
    "age": 30,
    "zip": "007",
    "active": true,
    "note": "Likes \"tea\", coffee\nand long walks"
  },
  {
    "name": "Bob",
    "age": 25,
    "zip": 90210,
    "active": false,
    "note": ""
  }
]

What happened

• The header row became the object keys; each data row became one object — two records, not three, even though the file spans four physical lines.
• age is the number 30 and active is the boolean true, because type detection is on by default.
• zip stayed the string "007" for Alice — converting it would destroy the leading zeros. Bob's 90210 has no leading zero, so it became a number.
• Alice's quoted note kept its internal comma and its line break; each doubled quote "" became a single " (escaped as \" in JSON).
• Bob's trailing empty cell became "" rather than being dropped.

Edge cases & gotchas

• Type detection is deliberately conservative. 007, 9007199254740993 and +15551234 stay strings, because converting them would silently change the value. Zip codes, product codes and phone numbers survive intact. Switch the option off entirely if you want every value as a string.
• A UTF-8 BOM is stripped automatically. Files exported from Excel often start with an invisible byte order mark. Left in place it becomes part of the first header name, so row.id silently returns undefined. The converter removes it and tells you it did.
• Duplicate headers are renamed, not dropped. A second column named id becomes id_2, because JSON keys must be unique. You get a notice rather than silent data loss.
• Ragged rows are tolerated. Missing trailing values become ""; extra cells beyond the header count are ignored. A notice reports how many rows were affected.
• Semicolon files are common outside the US. Excel in many European locales writes ; as the list separator. Auto-detect handles it, but you can force the delimiter if a file has an unusual header.

When to Use CSV to JSON

• When you have a spreadsheet export (Excel, Google Sheets) and need to load the data into a JavaScript application, REST API, or NoSQL database.
• When a data pipeline produces CSV output and a downstream step expects JSON as input.
• When importing bulk records (users, products, transactions) into an application that reads a JSON array.
• When you want to inspect CSV data using JSONPath or jq without writing a custom parser.