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JSON Lines Converter

Convert between JSON arrays and NDJSON, one compact document per line.

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Quick Tool Overview

The JSON Lines Converter moves between a JSON array and NDJSON, the one-document-per-line format used by log pipelines, BigQuery and Elasticsearch bulk loads. A broken line is reported by its line number.

What it does
Converts between JSON arrays and JSON Lines (NDJSON)
You give it
A JSON array, or a file with one document per line
You get back
The other format, with the record count confirmed
Best for
Log files, bulk loads, streaming APIs and BigQuery imports
Developer Tools Free, unlimited use No sign-up Runs in your browser

About the JSON Lines Converter

JSON Lines — also written NDJSON or .jsonl — puts one complete JSON document on each line with no wrapping array and no commas. It is the format log pipelines, BigQuery, Elasticsearch bulk loads and streaming APIs use, because a reader can process a line at a time.

This converter goes both ways. Turning an array into JSON Lines gives you a file that streams; turning JSON Lines into an array gives you something a normal JSON parser will accept. When a line fails to parse the error names the line number, which is the one thing that matters in a file of ten thousand records — a single bad line in the middle is otherwise almost impossible to find.

Key features of the JSON Lines Converter

Broken lines are located

A single bad record in ten thousand lines is reported by line number, which is otherwise almost impossible to find.

Both directions

Array to JSON Lines for streaming and appending; JSON Lines back to an array for anything that expects a normal document.

Record count confirmed

The number of records read is shown, so a truncated paste is obvious before you load the file anywhere.

Correct minification per line

Each record is written on exactly one line, which is the constraint the whole format depends on.

Right file extension

Downloads use .jsonl or .json to match the direction, so the file arrives named the way the receiving tool expects.

How to use the JSON Lines Converter

  1. 1

    Choose a direction

    Array to JSON Lines, or JSON Lines back to an array.

  2. 2

    Paste your data

    A JSON array of objects, or a file with one document per line.

  3. 3

    Check the record count

    The stat row confirms how many records were read, so a truncated paste is obvious.

  4. 4

    Copy or download

    Download as .jsonl or .json depending on the direction you converted.

Frequently asked questions

Nothing meaningful — they are three names for the same format. The .jsonl extension is the most common in practice, and .ndjson appears mostly in older tooling.

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