JSON (JavaScript Object Notation) is the universal language of data exchange on the web. Whether you're working with APIs, configuration files, or database records, valid JSON syntax is crucial. A single misplaced comma or missing bracket can break your entire application.
In this comprehensive guide, we'll explore everything you need to know about JSON validation, common errors, best practices, and how to use online validators to save hours of debugging time.
Validate and format JSON instantly with real-time error detection and line highlighting.
What is JSON Validation?
JSON validation is the process of checking whether a JSON string adheres to the JSON syntax rules defined in the RFC 8259 specification. Valid JSON must follow strict formatting rules:
- All strings must be enclosed in double quotes (not single quotes)
- Object keys must be strings
- No trailing commas after the last element in objects or arrays
- Proper nesting of objects and arrays
- Valid data types: string, number, boolean, null, object, array
Common JSON Syntax Errors
1. Trailing Commas
// ❌ Invalid - trailing comma
{
"name": "John",
"age": 30,
}
// ✅ Valid
{
"name": "John",
"age": 30
}Trailing commas after the last item are not allowed in JSON.
2. Single Quotes
// ❌ Invalid - single quotes
{'name': 'John'}
// ✅ Valid
{"name": "John"}JSON requires double quotes for all strings, including object keys.
3. Missing Commas
// ❌ Invalid - missing comma
{
"name": "John"
"age": 30
}
// ✅ Valid
{
"name": "John",
"age": 30
}Each key-value pair must be separated by a comma.
Why Use a JSON Validator?
Save Time
Instantly identify syntax errors instead of manually debugging
Auto-Format
Beautify minified JSON with proper indentation
Error Details
Get line numbers and specific error messages
Validation Confidence
Ensure your JSON is specification-compliant
How to Use Our JSON Validator
Paste Your JSON
Copy your JSON data from APIs, config files, or any source and paste it into the editor.
Click Validate
Press the validate button to check your JSON syntax instantly.
View Results
See validation results, error messages with line numbers, and formatted output.
Copy Formatted JSON
Copy the beautified JSON with proper indentation (2, 4, or 8 spaces).
Frequently Asked Questions
Is the JSON validator free to use?
Yes, our JSON validator is completely free with no limits on usage or file size.
Is my JSON data secure?
All validation happens in your browser. Your JSON data never leaves your computer.
Can I format minified JSON?
Yes, paste your minified JSON and our tool will beautify it with proper indentation and line breaks.
What do the error line numbers mean?
Error line numbers show exactly where the syntax error occurs, and the line is highlighted in red with the error context displayed.