NDJSON Validator

Check JSON Lines / NDJSON files line by line

Validate newline-delimited JSON (JSON Lines) — report line numbers and parse errors without uploading files.

Also known as: jsonl checker · validate ndjson · json lines validator · ndjson lint

100% In-Browser & Private — your data never leaves this device
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How to use the NDJSON Validator

  1. Paste NDJSON or drop a .jsonl / .ndjson file.
  2. Review per-line pass/fail with line numbers.
  3. Fix errors and re-validate — all processing stays local.

FAQ

What is NDJSON?
Newline-delimited JSON — one JSON value per line, common in streaming and log pipelines.
Is my file uploaded?
No. Parsing and validation run entirely in your browser.
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