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How to View and Format NDJSON Data

Parse, validate, and convert Newline Delimited JSON (NDJSON/JSON Lines) with ease

Step 1

Input Your NDJSON Data

Get your NDJSON data into the viewer! NDJSON (Newline Delimited JSON), also known as JSON Lines, stores one JSON object per line. You have several options:

•
Paste directly: Copy your NDJSON log output, streaming data, or file content and paste it into the input editor
•
Upload a file: Click "Upload" to select a .ndjson, .jsonl, or .txt file from your computer
•
Try the sample: Click "Sample" to load example NDJSON data and see how the viewer works

Example: NDJSON Input

Each line is a complete, valid JSON object:

{"id":1,"name":"Alice","role":"admin"}
{"id":2,"name":"Bob","role":"editor"}
{"id":3,"name":"Charlie","role":"viewer"}
Step 2

Automatic Parsing & Validation

The viewer instantly parses your NDJSON input line by line:

•
Line-by-line validation: Each line is parsed independently as a JSON object
•
Error detection: Invalid lines are flagged with specific error messages
•
Line counter: Shows total valid lines and error counts at a glance

Example: Formatted JSON Array Output

NDJSON lines are combined into a formatted JSON array:

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

Export Your Data

Get your parsed NDJSON data ready for use in your projects:

•
Copy to clipboard: One-click copying of the formatted JSON array output
•
Download as file: Save the output as a .json file for further processing
•
Validation status: Green checkmark confirms all NDJSON lines are valid

What is an NDJSON Viewer?

An NDJSON viewer parses and formats Newline Delimited JSON — a format where each line contains one valid JSON value as defined by RFC 8259. Also known as JSON Lines or JSONL, this format is widely used for streaming data, log files, and data pipelines because each line can be parsed independently.

This viewer is particularly useful when working with output from the Elasticsearch Bulk API, Google BigQuery exports, Apache Kafka consumers, and structured logging libraries. It validates each line using the browser's native JSON.parse(), giving you precise error locations for any malformed lines.

Unlike standard JSON viewers that require loading the entire document, NDJSON viewers process records line by line — making them far more efficient for large files. The viewer converts your NDJSON into a formatted JSON array, letting you use the data with any tool that accepts standard JSON. For deeper analysis, convert to table, CSV, or YAML.

Frequently Asked Questions

What is NDJSON?

NDJSON (Newline Delimited JSON), also called JSON Lines or JSONL, is a format where each line is a valid JSON value separated by newline characters. It's widely used for log files, streaming data, data pipelines, and big data processing because each line can be processed independently without loading the entire file into memory.

What is the difference between NDJSON and JSON?

Standard JSON (RFC 8259) wraps multiple objects in an array with commas between them. NDJSON places each JSON object on its own line with no commas or wrapping brackets. This makes NDJSON easier to stream, append to, and process in parallel — ideal for large datasets and log files that can't fit in memory.

Can I convert NDJSON to a regular JSON array?

Yes! This viewer automatically converts your NDJSON input into a formatted JSON array. Each line becomes an element in the array, making it compatible with any tool that expects standard JSON. Use our dedicated NDJSON to JSON converter for additional export options, or JSON to NDJSON to go the other direction.

What file extensions are used for NDJSON?

NDJSON files commonly use .ndjson or .jsonl extensions per the NDJSON specification and the JSON Lines site. Some tools also output .json or .txt files containing NDJSON-formatted data. This viewer accepts all of these file types for upload.

Where is NDJSON commonly used?

NDJSON is used by the Elasticsearch Bulk API, Google BigQuery data loading, Apache Kafka streams, MongoDB mongoexport, AWS Kinesis, and structured logging libraries (Pino, Bunyan, Winston). It's the preferred format when data needs to be appended or processed line by line.

Is the NDJSON viewer completely free?

Yes, totally free with no limitations on file size, usage frequency, or features. No registration required. All processing uses the browser's native JSON.parse() — your data never leaves your device.

Related Tools

NDJSON to JSON

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JSON to NDJSON

Convert a standard JSON array into NDJSON (Newline Delimited JSON) format. Transform JSON data for streaming, logging, and data pipelines.

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.