JSON Lines Validator

Runs in browser JSON & Data

Check NDJSON / JSONL content line by line. Blank lines are flagged, each parse error is reported with its line number, and valid records are counted.

Privacy: This tool runs entirely in your browser. Your input never leaves your device.

How to use JSON Lines Validator

  1. Paste the NDJSON / JSON Lines content.
  2. Read the summary and the table of invalid lines.
  3. Fix the reported lines and re-run before importing the file.

JSON Lines Validator features

  • Checks every line as an independent JSON value
  • Exact line and column for each failure plus a fix hint
  • Flags blank lines with their line numbers
  • Counts valid records and warns about mixed record types
  • Validates live as you paste
  • Error table exportable as CSV

JSON Lines Validator example

Spot a broken line in a log export

Input:

{"id":1,"event":"signup"}
{"id":2,"event":"login",}
{"id":3}

Output:

Line 2, column 24 — Invalid JSON. Trailing commas are not allowed before } or ].

Frequently asked questions about JSON Lines Validator

What exactly is checked?

Every non-blank line must be a complete, valid JSON value. Each failing line is reported with its number, column, the parser message and a hint; blank lines are flagged separately.

Are blank lines invalid?

Strict NDJSON parsers reject them, so they are reported as a warning with their line numbers even though the rest of the file may be valid.

Does it matter if lines are objects or arrays?

Any JSON value is allowed per line, but most consumers expect one object per line. A warning is shown when the record types are mixed.

Can I export the list of errors?

Yes — the invalid-lines table can be copied or downloaded as CSV for a bug report or a data-quality ticket.