Category: Developer tools
JSON Lines Converter
Convert between JSON Lines (NDJSON) and a JSON array
Convert JSON Lines (JSONL/NDJSON), one JSON value per line, into a single JSON array, or split a JSON array or object back into JSON Lines. Each row is validated on its own. Runs entirely in your browser.
3 of 3 line(s) parsed successfully.
[
{
"id": 1,
"name": "Ada Lovelace"
},
{
"id": 2,
"name": "Grace Hopper"
},
{
"id": 3,
"name": "Alan Turing"
}
]Everything on this page is processed in your browser. Nothing is uploaded.
What this tool does
JSON Lines is the format most log pipelines, ML datasets and streaming exports use: one complete JSON value per line, so a file can be read or appended to a line at a time. This tool parses each line independently, reporting how many parsed and where the first broken row is, then joins the valid values into one pretty-printed JSON array. The reverse direction takes a JSON array (or a single object) and prints one compact JSON value per line.
How to use it
- Choose JSONL to array, or array to JSONL.
- Paste your JSON Lines text or JSON array/object.
- Check the valid row count, then copy the converted 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 data uploaded anywhere?
- No. Parsing and conversion happen in JavaScript running in the page, so your JSON never leaves your device.
- What happens if one line is invalid JSON?
- That line is skipped and reported with its line number and the parser error, while every other valid line still converts.
- Can I convert a single JSON object, not just an array?
- Yes. A single object becomes one JSONL line; an array becomes one line per element.