Validate JSON Lines Independently without Losing Valid Records

How to Use This Tool

Parse each nonblank line separately, preserve order and expose partial failures. Validate NDJSON or JSON Lines record by record, pretty-print or minify valid objects, retain line errors, and download deterministic output locally.

The work this page finishes

A whole-file JSON parser fails at the first line and hides which later records remain valid; NDJSON needs independent per-line parsing and stable order. For NDJSON Formatter, a visible row-by-row result preserves provenance, making a single correction possible without rerunning unrelated records or uploading the batch.

Deterministic workflow

Ignore blank lines, parse every other line as one complete JSON value, optionally require an object or array, and preserve valid output plus line-numbered errors. For NDJSON Formatter, input guards stop after 5,000 records or 2 MB, and the report separates fatal input problems from recoverable row warnings.

Why a dedicated interface helps

Repair the reported source lines and rerun until all records pass; partial output is intentionally marked so it is not mistaken for a complete clean file. For NDJSON Formatter, deterministic ordering, one-click copying and a downloadable artifact make repeated operational review easier than manually reconstructing a response from prose.

Assumptions

• Each nonblank physical line is one complete JSON record.
• UTF-8 text is already decoded by the browser.
• Record order must remain unchanged.

For NDJSON Formatter, do not discard the source after export: compare the destination result with it, and remember that local execution cannot secure the surrounding device or browser add-ons.

Limitations and review boundary

It does not stream huge files, execute JSON, validate a JSON Schema, repair malformed records or guarantee an importing system's field requirements. For NDJSON Formatter, user values are never run as script, rendered as markup or fetched as network destinations; the page writes them only into text nodes.

Verification and provenance

On 2026-08-26, the rule and examples were cross-checked with NDJSON specification, including a known result, a rejected input and a conflict or duplicate case. The fixture keeps two valid objects, flags malformed line three and rejects the scalar null under object-only mode.