JSONL / NDJSON Formatter & Validator

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Validate, pretty-print, compact, sort and convert JSON Lines (NDJSON) files to and from JSON arrays, with per-line error reporting.

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Frequently Asked Questions

What is JSONL?

One JSON value per line, used for logs, LLM fine-tuning datasets and batch APIs.

Does it report the bad line?

Yes, every invalid line is listed with its line number and parser message.

Is my data uploaded?

No. Everything runs locally in your browser.

Format and beautify JSON data with syntax highlighting and collapsible tree view.

Minify and compress JSON by removing all whitespace.

Validate JSON syntax and get descriptive error messages with line numbers.