What is a JSONL File?

A JSONL file (file extension .jsonl) is a text file that contains multiple JSON objects, with each object on its own line. Each line in a .jsonl file is a complete, valid JSON object, separated by newline characters.

Example .jsonl File

Here's an example of what a .jsonl file looks like:

{"id": 1, "name": "John Doe", "email": "john@example.com", "age": 30}
{"id": 2, "name": "Jane Smith", "email": "jane@example.com", "age": 25}
{"id": 3, "name": "Bob Johnson", "email": "bob@example.com", "age": 35}

Each line in the file above is a complete JSON object. The file can be processed line by line, making it ideal for large datasets.

How .jsonl Files Work

JSONL files work differently from traditional JSON files:

[
  {"id": 1, "name": "John"},
  {"id": 2, "name": "Jane"}
]

{"id": 1, "name": "John"}
{"id": 2, "name": "Jane"}

When to Use .jsonl Files

Use .jsonl files when:

• Working with large datasets that don't fit in memory
• Streaming data in real-time
• Creating log files
• Preparing machine learning datasets
• Building data pipelines
• Processing data incrementally

How to Create .jsonl Files

You can create .jsonl files in several ways:

Python

import json

data = [{"id": 1, "name": "John"}, {"id": 2, "name": "Jane"}]

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

Using Our Tools

You can also create .jsonl files using our online tools:

• JSONL Generator - Create sample .jsonl files
• CSV to JSONL Converter - Convert CSV to .jsonl format
• JSON to JSONL Converter - Convert JSON arrays to .jsonl format

How to Read .jsonl Files

Reading .jsonl files is straightforward - process one line at a time:

Python

import json

with open('data.jsonl', 'r') as f:
    for line in f:
        data = json.loads(line.strip())
        process(data)

Using Our Tools

You can also view and work with .jsonl files using our online tools:

• JSONL Viewer - View and explore .jsonl files
• JSONL Validator - Validate .jsonl files for errors

File Extension Details

JSONL files can use different file extensions:

Learn More

For more information about JSONL file format:

• What is JSONL? - Introduction to JSON Lines
• JSON Lines Format Specification - Complete technical specification
• JSON Lines Format Definition - Formal definition
• JSONL for Developers - Implementation guide

Work with .jsonl Files