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JSONL to JSON converter

Convert JSONL to JSON free in your browser. Paste your JSON Lines on the left, press Convert, and copy clean JSON on the right. No sign-up, no uploads.

Converter

Paste JSON Lines below, press Convert, and copy the JSON output.

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How JSON Lines becomes JSON

Each non-empty line is parsed as its own JSON object and treated as one row, so a 10,000-line file is simply 10,000 rows. The converter collects the union of all keys across lines to build the column set, which means ragged objects with different keys still convert cleanly, with blanks where a line lacked a key.

Getting the best results

Press Load sample first to see the exact JSONL shape the converter expects, then replace it with your own data. If a conversion errors, the message names the exact line or token at fault, so fixing the input is usually a one-minute job. For repeated jobs, bookmark the page; your data never leaves the browser.

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JSONL to JSON FAQs

What exactly counts as JSON Lines input?
One complete JSON object per line, with no commas between lines and no outer array brackets. Each object becomes one row, and the union of all keys becomes the JSON columns. Blank lines are ignored, and the tool tells you the exact line number if one line fails to parse.
How is the JSON output formatted?
As a pretty-printed array of objects with two-space indentation, one object per row and null for missing cells. It validates as strict JSON, so you can paste it into APIs, config files or JavaScript with JSON.parse and it just works.
What about nested objects inside a line?
Nested objects and arrays are kept as compact JSON strings inside their cell, so nothing is dropped. If you need them flattened into dotted columns, convert to JSON first and flatten there; this tool keeps the JSON one row per line.
Is there a size limit for JSONL input?
No hard limit, but everything runs in your browser tab, so tens of thousands of rows convert in seconds while millions of rows may slow the page. For very large JSONL files, split them into smaller chunks and convert each separately.
Is my JSONL data private, and who uses this?
Yes. The conversion runs 100% in your browser; nothing is uploaded to any server. Developers, analysts and DBAs use it to move JSONL data into JSON for migrations, reports and config work without installing anything.
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