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JSON Lines to CSV

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Convert JSON Lines (JSONL/NDJSON) into CSV

Paste JSON Lines (one JSON object per line) to convert them into a CSV table, unioning every key seen across all lines into the column list. Invalid lines are reported with their line number. Runs entirely in your browser.

Parsed {count} row(s).: 2

CSV
name,role,active
Ada,Engineer,
Grace,Scientist,true

Everything on this page is processed in your browser. Nothing is uploaded.

What this tool does

Each non-blank line is parsed on its own as JSON, since that's what makes JSON Lines convenient for streaming; a line that isn't valid JSON, or that isn't a JSON object, stops the conversion with a message naming the exact line number so it's easy to find and fix in the source file. Because different lines in a real JSONL file don't always share the same keys, the column list is the union of every key seen across all lines, in the order each key first appeared, and a line missing a given key gets an empty cell for it in the output.

How to use it

  1. Paste JSON Lines, or load the example.
  2. Review the parsed row count and any line-numbered error.
  3. Copy the CSV result.

Privacy

This tool runs entirely in your browser. Your input is never uploaded, stored or shared — closing the tab removes it.

Frequently asked questions

Is my JSON Lines file uploaded anywhere?
No. Parsing happens in JavaScript running in the page, so nothing you paste ever leaves your device.
What happens if one line is invalid?
The conversion stops and reports the exact line number along with the parser's own message, or a note that the line isn't a JSON object, instead of silently skipping it.
What if lines have different keys?
The CSV columns are the union of every key seen across all lines; a line that's missing a particular key simply gets an empty cell for that column.

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