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JSON / JSON Lines Converter
Convert JSON arrays to JSON Lines and restore arrays while preserving exact number tokens and record order.
JSON array, NDJSON / JSON Lines, UTF-8 JSON, JSONL, NDJSON or text file
NDJSON, JSON array
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
This tool needs JavaScript. If it does not load, refresh the page and try again.
How to use this tool
- Choose JSON array to NDJSON or NDJSON to JSON array.
- Paste input or choose a UTF-8 file; a selected file takes precedence.
- Select Convert records. Fix any error using its original record line number.
- Download converted.ndjson or converted.json. Editing input clears the previous download.
Examples
Convert [{"id":9007199254740993},null,true] into three NDJSON records while retaining the complete integer token.
Limitations
- Forward conversion requires a JSON array. Reverse conversion accepts one complete JSON value per physical LF record, with CRLF also accepted and one optional final line terminator. Blank records are rejected; an empty stream represents an empty array.
- Up to 5 MiB input, 50,000 records, 200,000 total values including the array, 40 nesting levels including the array, 10,000 characters per numeric token and 20 MiB output.
- Strict JSON only: duplicate object keys, malformed Unicode, comments and trailing commas are rejected.
- Nonempty NDJSON output ends in LF. JSON array output is formatted with indentation. Pasted textarea line endings normalize to LF.
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