How to Format JSON Online: A Complete Guide

JSON (JavaScript Object Notation) is the most popular data format for APIs and configuration files. However, minified or unformatted JSON can be difficult to read. This guide shows you how to format JSON online quickly and easily.

What is JSON Formatting?

JSON formatting (also called beautifying or pretty-printing) adds proper indentation, line breaks, and spacing to JSON data. This makes it human-readable without changing the data itself.

Before formatting:

{"name":"John","age":30,"city":"New York","skills":["JavaScript","Python","Go"]}

After formatting:

{
  "name": "John",
  "age": 30,
  "city": "New York",
  "skills": [
    "JavaScript",
    "Python",
    "Go"
  ]
}

How to Format JSON Online (Step-by-Step)

Step 1: Open a JSON Editor

Go to jsoneditor.io in your web browser. The editor loads instantly with no signup required.

Step 2: Paste Your JSON

Copy your unformatted JSON and paste it into the editor. You can also:

• Drag and drop a .json file directly into the browser
• Use Ctrl+V (Windows) or Cmd+V (Mac) to paste

Step 3: Click Format

Click the Format or Pretty button in the toolbar. Your JSON will be instantly beautified with:

• 2-space indentation (configurable)
• Proper line breaks
• Aligned colons and values

Keyboard shortcut: Press Shift+Alt+F to format instantly.

Common JSON Formatting Issues

Invalid JSON Errors

If your JSON won't format, it likely contains syntax errors:

• Missing commas between key-value pairs
• Unquoted keys (JSON requires double quotes)
• Trailing commas after the last item
• Single quotes instead of double quotes

The jsoneditor.io editor highlights these errors with red underlines and provides suggestions to fix them.

Large JSON Files

For large JSON files (megabytes of data), online formatters can be slow. jsoneditor.io handles files up to 512MB efficiently because all processing happens in your browser.

Why Format JSON?

1. Debugging - Easier to spot missing values or incorrect structures
2. Code reviews - Formatted JSON is easier to compare in pull requests
3. Documentation - Readable JSON in docs helps other developers
4. API testing - Quickly understand API response structures

JSON Formatting Best Practices

• Use 2 spaces for indentation (industry standard)
• Keep arrays of primitives on one line when short
• Use consistent key ordering (alphabetical or logical grouping)
• Validate before formatting to catch errors early

Frequently Asked Questions

Is online JSON formatting safe?

Yes, when using tools like jsoneditor.io. All processing happens locally in your browser. Your data is never uploaded to any server.

Can I format JSON in the command line?

Yes, use jq or Python:

# Using jq
echo '{"name":"John"}' | jq .

# Using Python
echo '{"name":"John"}' | python -m json.tool

What's the difference between JSON and JSON5?

JSON5 is an extension that allows comments, trailing commas, and unquoted keys. Standard JSON does not support these features.

Summary

Formatting JSON makes it readable and easier to work with. Use jsoneditor.io to format JSON instantly in your browser with no signup required. The editor also validates your JSON and highlights any syntax errors.