NDJSON to JSON Converter

About this tool

Log exports, database dumps and inference outputs all tend to arrive as NDJSON, because writing one record per line is the cheapest thing a producer can do. Reading them is another matter: most JSON tooling expects a single document, so the first step is nearly always to combine the lines into an array.

The useful part is what happens when it goes wrong. In a 50,000-line export, one truncated record is entirely normal, and the only thing that matters is which line it is. Errors here carry the line number from the source file, so it matches what your editor shows.

Blank lines are skipped rather than treated as errors, and reported in the warnings so a file full of them does not pass unremarked.

How to use this tool

1. 1

   Paste NDJSON, or upload a .ndjson, .jsonl or .log file.

2. 2

   Choose the indentation for the resulting array.

3. 3

   Press Convert.

4. 4

   If a line fails, use the reported line number to find it in the source.

Key features

• Every line parsed as an independent JSON value
• Errors reported with the line number from the source file
• The offending line shown as an excerpt alongside the error
• Blank lines skipped and counted rather than treated as failures
• Tolerant of CRLF line endings on input
• Record count reported so you can check nothing was lost

Example

{"id":101,"name":"Ha-eun"}
{"id":102,"name":"Marco"}

[
  {
    "id": 101,
    "name": "Ha-eun"
  },
  {
    "id": 102,
    "name": "Marco"
  }
]

Good to know

Frequently asked questions

Further reading

What is NDJSON? — NDJSON is JSON with one complete value on each line and no array around it. That one change is what makes a file streamable — and what breaks it if you pretty-print it.