Convert CSV to JSON Lines

CSV to JSON Lines Converter — frequently asked questions

How do I convert CSV to JSON Lines?

Paste your CSV, or open or drop a file, and the JSON Lines appears instantly. Copy it, download it (named after your file), or open it in another tool. Errors point to the line and column. Everything happens in your browser.

Does it use the first row as headers, and keep my zip codes?

Yes. The first row is the column names. Each column gets one type: numbers only when every value is a plain number, so zip codes and ids like 01234 stay text with their leading zeros. Tick "Keep values as text" to read everything as text. A file with one column works, and short rows are padded and listed by line number.

How does JSON Lines map to JSON?

Each non-empty line is one JSON value, and together they make a JSON list; a list written as JSON Lines puts each item on its own line. A line that isn't valid JSON is reported by its line number.

Is my data uploaded to a server?

No. The conversion runs entirely in your browser — your data never leaves your device, so it's safe to convert configuration, API payloads, and other sensitive files. You can even go offline once the page has loaded.

Is this converter really free?

Yes. No sign-up, no payment details, no file-size paywall, and no watermark on the output.