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NDJSON Formatter / Validator

Data

Format, validate, and convert newline-delimited JSON (NDJSON/JSON Lines), one JSON value per line

Paste newline-delimited JSON, the format most log pipelines and streaming APIs actually use, and get each line validated independently, with the exact line number reported the moment something breaks rather than one generic parse error for the whole file. It also pretty-prints or minifies the whole document, and converts between NDJSON and a single JSON array when a downstream tool expects one format but you have the other. Formatting and minifying both stop at the first invalid line rather than trying to skip past it, so fixing errors top to bottom is the practical workflow. It's comfortable up to tens of megabytes in the browser; for genuinely large multi-gigabyte log files, a command-line tool like `jq` is the better fit.

ndjsonjson-linesformatvalidatestreaming

How to use NDJSON Formatter / Validator

  • 1.Paste NDJSON log output (one JSON object per line) to validate that every line parses correctly and spot the exact line number of a malformed entry.
  • 2.Format a minified NDJSON stream into pretty-printed, indented JSON per line for easier manual inspection.
  • 3.Convert an NDJSON file into a single JSON array when you need to load it into a tool that expects standard JSON rather than line-delimited records.

Frequently asked questions

What's the difference between NDJSON and a JSON array?
NDJSON stores one complete JSON value per line with no surrounding brackets or commas, which makes it easy to stream, append to, and process line-by-line, unlike a JSON array which must be parsed as a whole.
Is my data sent to a server?
No, validation and formatting happen entirely in your browser.
Can it handle very large NDJSON files, like multi-GB log exports?
It works well for typical files up to tens of MB in the browser, but for multi-GB streaming logs you're better off using a command-line tool like `jq` that processes line-by-line without loading everything into memory.
Does it validate that each line is valid JSON, or just that the file looks right overall?
It validates each line independently and reports the exact line number if one fails to parse, since a single bad line in NDJSON shouldn't invalidate the rest of the stream.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/ndjson-format \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"input": "{\"a\":1}\n{\"b\":2}"}'

Get an API key from your dashboard · Full API docs →

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