JSON to NDJSON Converter: Transform JSON Arrays to Newline Delimited JSON

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Convert JSON arrays to NDJSON (Newline Delimited JSON) format with support for nested structures, data cleaning options, and bulk processing. Perfect for ETL pipelines, log processing, and data streaming.

✓ Nested Structure Support✓ Data Cleaning Options✓ NDJSON Download

JSON Input

NDJSON Output

What is NDJSON?

NDJSON (Newline Delimited JSON) is a convenient format for storing or streaming structured data that may be processed one record at a time. It's also known as JSON Lines or JSONL.

Each line in an NDJSON file is a valid JSON object, and lines are separated by newline characters. This format makes it easy to:

  • Process large datasets one record at a time
  • Append new records without loading the entire file
  • Stream data between systems efficiently
  • Parse records progressively with minimal memory overhead
  • Import data into databases and data processing tools

Unlike standard JSON arrays that require the entire dataset to be loaded into memory, NDJSON can be processed line by line, making it ideal for working with large datasets.

Converter Features

Input Processing

  • •

    Array Conversion

    Transform JSON arrays into line-delimited objects

  • •

    Nested Structure Support

    Preserves complex nested objects and arrays

  • •

    Validation Options

    Ensure each array item is a valid JSON object

Data Cleaning

  • •

    Null Value Handling

    Option to strip null values from output

  • •

    String Trimming

    Remove leading/trailing whitespace from strings

  • •

    Export Options

    Copy to clipboard or download as .ndjson file

Common Use Cases

Data Engineering

  • • ETL pipeline processing
  • • Data lake ingestion
  • • Stream processing
  • • Log file generation

Database Operations

  • • MongoDB data import
  • • Elasticsearch bulk indexing
  • • NoSQL database loading
  • • Database migration

API & Development

  • • API response formatting
  • • Microservice data exchange
  • • Event streaming
  • • Serverless function input

JSON vs NDJSON Format Comparison

Standard JSON Array

[
  {"id": 1, "name": "Alice", "role": "admin"},
  {"id": 2, "name": "Bob", "role": "user"},
  {"id": 3, "name": "Carol", "role": "editor"}
]

Equivalent NDJSON

{"id": 1, "name": "Alice", "role": "admin"}
{"id": 2, "name": "Bob", "role": "user"}
{"id": 3, "name": "Carol", "role": "editor"}

JSON Pros/Cons

  • ✓ Valid single JSON document
  • ✓ Widely supported
  • ✓ Maintains array relationship
  • ✗ Entire file must be loaded in memory
  • ✗ Difficult to append without rewriting
  • ✗ Cannot stream/process incrementally

NDJSON Pros/Cons

  • ✓ Process one record at a time
  • ✓ Append new records easily
  • ✓ Memory efficient for large datasets
  • ✓ Streamable format
  • ✗ Not a single valid JSON document
  • ✗ Requires specific parsing approach

Working with NDJSON

Reading NDJSON in Node.js

const fs = require('fs');
const readline = require('readline');

// Read and process NDJSON file line by line
async function processNDJSON(filePath) {
  const fileStream = fs.createReadStream(filePath);
  const rl = readline.createInterface({
    input: fileStream,
    crlfDelay: Infinity
  });

  for await (const line of rl) {
    if (line.trim() === '') continue;
    
    try {
      const record = JSON.parse(line);
      // Process each record...
      console.log('Processing record:', record.id);
    } catch (err) {
      console.error('Error parsing line:', line);
    }
  }
}

processNDJSON('data.ndjson');

Writing NDJSON in Python

import json

# Sample data
data = [
    {"id": 1, "name": "Alice", "role": "admin"},
    {"id": 2, "name": "Bob", "role": "user"},
    {"id": 3, "name": "Carol", "role": "editor"}
]

# Write data as NDJSON
with open('output.ndjson', 'w') as f:
    for record in data:
        f.write(json.dumps(record) + '\n')

# Reading NDJSON
records = []
with open('output.ndjson', 'r') as f:
    for line in f:
        if line.strip():
            records.append(json.loads(line))

Frequently Asked Questions

Why use NDJSON instead of JSON?

NDJSON is ideal for large datasets that need to be processed incrementally or for data that's continuously appended. Each record is a standalone JSON object on its own line, allowing for processing one line at a time without loading the entire dataset into memory. This makes NDJSON perfect for log files, data streaming, and ETL processes where efficiency is crucial.

Which databases support NDJSON?

Many modern databases and data processing tools support NDJSON natively or through import utilities. MongoDB, Elasticsearch, and BigQuery all provide direct NDJSON import capabilities. Apache Spark, Hadoop, and most data processing frameworks can easily read NDJSON files as well. For databases without direct support, the line-by-line nature makes it easy to build custom importers.

How do I convert NDJSON back to JSON?

To convert NDJSON back to a standard JSON array, you need to read each line, parse it as JSON, add each object to an array, and then serialize the entire array back to JSON. Most programming languages provide simple ways to do this, and many data processing tools offer this conversion as a built-in feature.

Is my data secure when using this converter?

Yes, all processing happens entirely in your browser. No data is sent to any server, ensuring your information remains private and secure. This tool processes your JSON locally, which also means it can handle large datasets without network transfer delays.

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