JSONL to CSV Converter

Runs in your browser — your files are never uploaded.

Convert JSON Lines — one JSON object per line, the format that BigQuery, Snowflake, logging pipelines and most LLM training sets export — into a CSV you can open in a spreadsheet. Every key that appears anywhere gets a column, so a field only some records carry is not silently dropped, and nested values are written as JSON in the cell so they stay re-parseable. Runs entirely in your browser.

How to convert JSONL to CSV

  1. 1

    Drop your .jsonl or .ndjson file onto the box, or click to choose one.

  2. 2

    Every record is read and the column set is built from all of them.

  3. 3

    Click “Download” to save your .csv file.

Share

Embed this tool on your site

Paste this where you want the tool to appear. It runs entirely in your visitor's browser — no uploads, no account, no tracking.

Please keep the attribution line — it's what keeps these tools free.

Need a different size, a dark theme, or a different tool? Build an embed lets you preview it first.

Frequently asked questions

What if my records do not all have the same fields?+

Every key that appears anywhere becomes a column, in the order first seen, and records missing it get an empty cell. Taking the columns from the first line only is the common shortcut, and it quietly discards data in exactly the exports where it matters.

What is the difference between JSONL and NDJSON?+

Nothing that affects this tool — both mean one JSON value per line. The names come from different communities; JSON Lines and Newline-Delimited JSON are used interchangeably.

How are nested objects and arrays handled?+

They are written into the cell as JSON. It is not pretty, but it is lossless and parseable — flattening a nested list into "a, b, c" would destroy the boundary between one value containing a comma and two separate values.

What happens if one line is malformed?+

Conversion stops and the error names the line number and shows the start of the offending text. In a 10,000-line export that is the difference between a fixable problem and an unusable file.

Related conversions