JSONL to CSV Converter

JSONL, also called NDJSON or JSON Lines, stores one complete JSON object per line separated by newlines. It is common for logs, database exports, and streaming data because each line can be read and written independently.

The header is the union of every key seen across all lines, kept in the order each key first appears. If a later record introduces a new key, that column is appended to the right, and earlier rows leave it blank.

Any cell that contains a comma, a double quote, or a line break is wrapped in double quotes, and each inner quote is doubled. Cells without those characters are left unquoted. This follows RFC 4180 so spreadsheets read it correctly.

A nested value is serialized as compact JSON inside its cell, so a value like an array of two numbers becomes the text [1,2] in that column. If that JSON contains a comma it is quoted like any other special value.

A JSON null and a key that a row simply does not have both render as an empty cell. Numbers and booleans are written as their plain text, so true stays true and 42 stays 42.

Yes. Click CSV to JSONL and the first row becomes the keys, then each following row becomes one JSON object per line. Every cell comes back as a string, since CSV does not record whether a value was a number or text.

Structure survives but types do not. Going JSONL to CSV and back leaves numbers, booleans and nested JSON as plain strings, because CSV has no type information to restore them from.

The generated CSV joins rows with CRLF, the carriage return plus line feed pair that RFC 4180 specifies, which is what Excel and most spreadsheet tools expect on import.

No. Both conversions run in your browser, so your JSONL and CSV never leave your device and nothing is logged or stored.