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Free JSON Formatter & Validator Online

Instantly format, validate, beautify and minify your JSON data. Get syntax highlighting, interactive tree view, and detailed error messages. 100% free, works offline, no sign-up needed.

📂 Load Sample JSON:

Actions:
Indent:
📥 Input Raw JSON
📤 Output
// Formatted output will appear here...
❌ Invalid JSON
📝 Lines:
🔑 Keys:
📊 Depth:
📐 Raw Size:
✨ Formatted:
📦 Minified:

🌲 Interactive Tree View

Format or validate JSON above to see the interactive tree view.
🌲 Tree view will appear here after you format valid JSON.
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⚠️ Common JSON Errors & How to Fix Them

JSON has strict syntax rules. Here are the most common mistakes developers make:

❌ Error Trailing Comma

WRONG ❌

{"name": "John",
"age": 30,   ← comma here
}

CORRECT ✅

{"name": "John",
"age": 30
}
❌ Error Single Quotes Instead of Double Quotes

WRONG ❌

{'name': 'John'}

CORRECT ✅

{"name": "John"}
❌ Error Unquoted Keys

WRONG ❌

{name: "John"}

CORRECT ✅

{"name": "John"}
❌ Error Comments in JSON

WRONG ❌

{ // user data
  "name": "John"
}

CORRECT ✅

{
  "name": "John"
}

📖 How to Use the JSON Formatter

1

Paste Your JSON

Click inside the dark Input panel on the left and paste your raw JSON using Ctrl+V. Or click one of the Sample JSON buttons to load an example instantly.

2

Click Format

Click the ✨ Format button to beautify your JSON with syntax highlighting in the output panel. Use the Indent selector to choose 2 spaces, 4 spaces, or tabs.

3

Explore the Tree View

Scroll down to the Interactive Tree View to explore your JSON structure. Click any object or array to collapse or expand it.

4

Copy or Minify

Click 📋 Copy to copy the formatted output, or 📦 Minify to get the smallest possible JSON string for production use.

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❓ Frequently Asked Questions

What is JSON? +
JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format. It is human-readable and easy to parse. JSON is the most widely used format for transmitting data between web servers and browsers (APIs), and for storing configuration files.
What is the difference between formatting and minifying JSON? +
Formatting (Beautifying) adds indentation and line breaks to make JSON easy to read by humans. It is ideal during development and debugging.

Minifying removes all whitespace and line breaks to produce the smallest possible JSON string. It is used in production to reduce file size and speed up data transfer.
How do I fix a JSON error? +
Paste your broken JSON and click Auto-Fix — the tool will attempt to fix common issues like trailing commas and single quotes. If it cannot be auto-fixed, the error message will tell you the exact position of the problem so you can fix it manually.
What are the JSON data types? +
JSON supports 6 data types:

String"hello"
Number42 or 3.14
Booleantrue or false
Nullnull
Object{"key": "value"}
Array[1, 2, 3]
Is my JSON data private when I use this tool? +
Yes, completely. All formatting, validation, and parsing happens 100% inside your browser using JavaScript. Your JSON data is never sent to any server, never stored, and never logged. You can even use this tool offline.
Can I format large JSON files? +
Yes. There is no imposed size limit. The tool processes all JSON directly in your browser. Very large JSON files (multiple MB) may be slower depending on your device's processing power, but they will still work.