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How to Convert JSON to NDJSON

Transform JSON arrays into Newline Delimited JSON (NDJSON/JSON Lines) format

Step 1

Input Your JSON Array

Paste a JSON array into the input editor. The converter accepts standard JSON arrays where each element will become a separate NDJSON line.

•
Paste directly: Copy your JSON array from an API response, file, or code editor
•
Upload a file: Click "Upload" to select a .json or .txt file
•
Try the sample: Click "Sample" to see a working example

Example: JSON Array Input

A standard JSON array with employee records:

[
  {"id": 1, "name": "Alice Johnson", "department": "Engineering", "salary": 95000},
  {"id": 2, "name": "Bob Smith", "department": "Marketing", "salary": 82000},
  {"id": 3, "name": "Charlie Lee", "department": "Engineering", "salary": 105000},
  {"id": 4, "name": "Diana Ross", "department": "Sales", "salary": 78000}
]
Step 2

Automatic Conversion

Each array element is serialized as a compact JSON object on its own line — following the NDJSON specification:

•
One object per line: Each array element becomes a single-line JSON string
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No separators: Lines are separated by newlines only — no commas or brackets
•
Line count: Shows the total number of NDJSON lines generated

Example: NDJSON Output

Each line is an independent, self-contained JSON object:

{"id":1,"name":"Alice Johnson","department":"Engineering","salary":95000}
{"id":2,"name":"Bob Smith","department":"Marketing","salary":82000}
{"id":3,"name":"Charlie Lee","department":"Engineering","salary":105000}
{"id":4,"name":"Diana Ross","department":"Sales","salary":78000}
Step 3

Export Your NDJSON

Get the NDJSON output ready for your data pipeline:

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Copy to clipboard: One-click copying of the NDJSON output
•
Download as .ndjson: Save as a .ndjson file for streaming, logging, or data import
•
Ready to stream: NDJSON output is immediately usable with streaming tools and data pipelines

What is NDJSON (Newline Delimited JSON)?

NDJSON (Newline Delimited JSON), also known as JSON Lines or JSONL, is a text-based data format where each line contains a valid JSON value. Unlike standard JSON arrays defined in RFC 8259, NDJSON does not require wrapping brackets or commas between records, making it ideal for streaming and append-only operations.

NDJSON is the preferred format for tools like the Elasticsearch Bulk API, Google BigQuery data loading, Apache Kafka message streams, and structured logging systems. Converting JSON arrays to NDJSON enables efficient line-by-line processing without loading entire datasets into memory.

Each line in an NDJSON file is parsed independently using JSON.parse(), which means a single malformed line won't corrupt the entire dataset — a key advantage over standard JSON arrays for data pipeline reliability.

JSON Array vs NDJSON Format

Understanding when to use standard JSON arrays versus NDJSON format helps you choose the right approach for your data processing needs:

Standard JSON Array

All data wrapped in a single array structure. Must be fully loaded into memory for parsing. Best for APIs, configuration, and smaller datasets.

JSON ValidatorJSON ViewerJSON Formatter

Best for: REST APIs, config files, frontend applications, small datasets

NDJSON / JSON Lines

One JSON object per line with no wrapping structure. Can be streamed and processed line-by-line. Best for logging, data pipelines, and large datasets.

NDJSON ViewerNDJSON ValidatorNDJSON to CSV

Best for: Log files, Elasticsearch, BigQuery, Kafka, streaming APIs

Frequently Asked Questions

Why convert JSON to NDJSON?

NDJSON is ideal for streaming data, log files, and data pipelines because each line can be processed independently without loading the entire file into memory. This makes it much more efficient for large datasets. Use our NDJSON Viewer to inspect the output, or NDJSON Validator to verify it.

What if my input is a single JSON object?

Single JSON objects are output as a single NDJSON line. For the best results, use a JSON array where each element becomes its own line in the NDJSON output. You can use our JSON Validator to check your input first.

Can I convert NDJSON back to JSON?

Yes! Use our NDJSON to JSON converter to transform NDJSON back into a standard JSON array. You can also convert NDJSON to other formats like CSV or view it as a table.

What tools and services use NDJSON?

NDJSON is used by the Elasticsearch Bulk API, Apache Kafka, AWS Kinesis, Google BigQuery, MongoDB exports, structured logging systems, and many data processing pipelines.

What is the difference between NDJSON, JSON Lines, and JSONL?

They are the same format with different names. NDJSON (Newline Delimited JSON), JSON Lines, and JSONL all refer to the same convention: one valid JSON value per line, separated by newline characters. The file extensions .ndjson, .jsonl, and sometimes .json are all used interchangeably.

Is this converter free?

Yes, completely free with no limits. All processing happens in your browser — your data never leaves your device.

Related Tools

NDJSON Viewer

View, validate, and format NDJSON (Newline Delimited JSON) data. Parse each line, detect errors, and convert to formatted JSON arrays.

NDJSON to JSON

Convert NDJSON (Newline Delimited JSON) to a standard JSON array. Transform JSON Lines data into formatted JSON for APIs, databases, and tools.

NDJSON to CSV

Convert NDJSON (Newline Delimited JSON) to CSV format. Transform JSON Lines data into spreadsheet-compatible CSV with automatic header detection.

NDJSON to Table

Convert NDJSON (Newline Delimited JSON) to a readable HTML table. Visualize JSON Lines data in rows and columns with color-coded types and CSV export.

NDJSON Validator

Validate NDJSON (Newline Delimited JSON) data line by line. Check JSON Lines syntax with detailed error messages and type detection.

NDJSON to YAML

Convert NDJSON (Newline Delimited JSON) to YAML format. Transform JSON Lines data into clean, human-readable YAML.