CSV to JSON Converter – and JSON to CSV

How to use the CSV to JSON converter

1. Choose CSV → JSON or JSON → CSV.
2. Paste your data, or press Try an example.
3. Choose the delimiter or leave it on automatic detection.
4. For CSV → JSON, choose whether the first row is a header and whether to convert numbers and true/false.
5. Copy the result or Download it as a file.

How the conversion works

CSV → JSON with a header row: the first row gives the keys; every following row becomes an object.

name,country,score
Ada,UK,98

becomes

[{"name": "Ada", "country": "UK", "score": 98}]

Without a header, each row becomes an array of values.

JSON → CSV: the input must be an array. For an array of objects, the header row is every key found; missing values become empty cells. For an array of arrays, each inner array is one row.

CSV rules the converter follows

• Fields are separated by the delimiter.
• A field containing the delimiter, a double quote or a line break is wrapped in double quotes.
• A double quote inside a quoted field is written twice: "say ""hi""".
• Lines can end with Windows (CRLF) or Unix (LF) line breaks.
• Empty lines are ignored.

Working with Excel and Google Sheets

To get CSV from a spreadsheet, use File → Download → CSV in Google Sheets or Save As → CSV in Excel. To open converted CSV in Excel with accents and non-Latin characters intact, import it using UTF-8 encoding (Data → From Text/CSV). Excel in many European languages expects semicolons, so choose the semicolon delimiter when exporting JSON to CSV for those users.

Large files

The converter works on files of several megabytes in a modern browser. For very large exports — hundreds of thousands of rows — a command-line tool or a script is faster. Because everything happens on your device, the limit is your device’s memory, not an upload size. If the browser becomes slow, split the CSV into smaller parts and convert each one.

Data types and leading zeros

CSV has no data types: everything is text. When “Convert numbers” is on, values that look like numbers become JSON numbers, but values with leading zeros — postcodes, ZIP codes, phone numbers and product codes such as 00123 — are left as text so the zeros aren’t lost. If a column must always stay text, turn the option off.

Common uses

• Turning a spreadsheet into data for a website, app or API.
• Creating test fixtures and seed data.
• Exporting API results to a spreadsheet for analysis.
• Moving data between tools that speak different formats.

Tidy your JSON with the JSON formatter, or convert configuration files with YAML to JSON.