View and Validate JSON Lines Records
JSON Lines (JSONL) stores each record as its own single line of JSON — a format commonly used for machine-learning datasets, application logs and streaming data. Large JSONL files are hard to scan in a plain text editor. This viewer parses every line and shows one pretty-printed, syntax-highlighted record at a time.
One Record at a Time
Navigate your file with the Prev and Next buttons, or jump straight to any line number. Each record is shown fully formatted, so it is far easier to read than the raw, single-line representation.
Instant Validation
Every non-empty line is parsed as it loads. The summary bar shows the total number of lines along with valid and invalid counts, and any bad lines are listed with their line number and the exact error message.
Syntax-Highlighted Output
Keys, strings, numbers, booleans and null values are each color-coded, which makes individual fields easy to pick out inside a large record.
Private and Offline-Ready
Everything runs client-side in your browser's own JavaScript engine. Your JSONL data is never uploaded, so the tool is safe for sensitive datasets.