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JSON Validator

Validate JSON online free. Check syntax, find errors, and get detailed messages.

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💡 Common JSON Issues to Check:

  • • Missing quotes around object keys ({key: "value"} should be {"key": "value"})
  • • Trailing commas before closing brackets ([1, 2,] should be [1, 2])
  • • Single quotes instead of double quotes ('key': 'value' should be "key": "value")
  • • Unescaped special characters in strings ("Hello\nWorld" needs escaping)
  • • Missing commas between array/object elements

How to Validate JSON Online Free

  • Paste your JSON data into the input field or upload a JSON file
  • Click "Validate JSON" to check the syntax and structure
  • Review any error messages with line numbers and detailed explanations
  • Use the auto-fix feature to automatically correct common JSON errors
  • Format your validated JSON for better readability
  • Copy the validated JSON or download it as a file
  • Minify your JSON after validation for production deployment
  • Compress your JSON for maximum size reduction if needed

Why Validate JSON for Developers

Catch Errors Early

Identify JSON syntax errors, missing commas, and structural issues before they cause problems in your applications. Use our JSON syntax checker to catch issues early.

Ensure Data Integrity

Validate that your JSON conforms to proper specifications and contains all required fields. Check JSON structure with our JSON format checker.

Debug API Responses

Quickly validate API JSON response data and identify issues with data formatting. Perfect for debugging JSON from REST APIs.

Auto-Fix Common Issues

Automatically correct invalid JSON with our JSON syntax fixer. Fix trailing commas, missing quotes, and other common JSON formatting errors.

Common JSON Errors & How to Fix Them

Trailing Commas

❌ Wrong:

{"name": "John", "age": 30,"}

✅ Correct:

{"name": "John", "age": 30}

Missing Quotes on Keys

❌ Wrong:

{name: "John", age: 30}

✅ Correct:

{"name": "John", "age": 30}

Single Quotes Instead of Double

❌ Wrong:

{"}name': 'John', 'age': 30{"}

✅ Correct:

{"name": "John", "age": 30}

Missing Commas Between Items

❌ Wrong:

["item1" "item2" "item3"]

✅ Correct:

["item1", "item2", "item3"]

Unescaped Special Characters

❌ Wrong:

{"text": "Hello\nWorld"}

✅ Correct:

{"text": "Hello\\nWorld"}

Invalid Numbers

❌ Wrong:

{"price": 123.45.67}

✅ Correct:

{"price": 123.45}

💡 Pro Tip

Our JSON validator automatically detects and can fix most of these common errors. Enable "Auto-fix" in the options to automatically correct syntax issues while validating.

JSON Specifications Supported

RFC 8259

The current JSON specification (2017) - most widely used and recommended.

RFC 7159

Updated specification (2014) with clarifications and minor corrections.

RFC 4627

Original JSON specification (2006) - still widely supported.

Learn more about ECMA-404 and JSON Schema validation.

Common JSON Errors We Can Fix

Missing Quotes Around Keys

Invalid: {name: "John"}

Fixed: {"name": "John"}

Trailing Commas

Invalid: {"name": "John",}

Fixed: {"name": "John"}

Single Quotes Instead of Double

Invalid: {'name': 'John'}

Fixed: {"name": "John"}

JSON Validation Resources & Tools

📋 Validation Standards

🧪 Testing Frameworks

📚 API Documentation

🔧 Development Tools

📖 Learning Resources

🌐 Related Communities

Frequently Asked Questions About JSON Validation

What is JSON validation?

JSON validation is the process of checking whether a JSON document conforms to the JSON specification (RFC 8259) and contains valid syntax. This includes checking for proper brackets, quotes, and data structure formatting.

Why should I validate JSON?

Validating JSON catches syntax errors early, prevents runtime issues, ensures data integrity, and makes debugging easier. It's especially important when working with APIs, configuration files, and data interchange.

What are common JSON errors?

Common errors include missing commas, unescaped quotes, trailing commas, incorrect bracket pairing, and using single quotes instead of double quotes. Our validator catches these and provides specific error messages.

Can the validator fix my JSON automatically?

Yes! Our JSON validator has an auto-fix feature that can automatically correct many common JSON errors like trailing commas, missing quotes, and incorrect bracket pairing.

Is my data safe when validating online?

Absolutely! All JSON validation happens entirely in your browser using JavaScript. Your data never leaves your computer and is never sent to any server.

What JSON specifications are supported?

We support RFC 8259 (current standard), RFC 7159, and RFC 4627. These specifications define the valid syntax for JSON documents including data types, encoding, and structural requirements.

Can I validate very large JSON files?

Yes, you can upload JSON files directly to the validator. Performance depends on your browser and system resources, but most modern browsers can handle files up to several MB.

What's the difference between a JSON validator and a linter?

A validator checks if JSON is syntactically correct. A linter goes further by checking code style, best practices, and potential issues. Our tool combines both functionalities.

Does the validator support JSON Schema?

Our validator checks JSON against the JSON specification. For validating against custom schemas (JSON Schema), consider using specialized tools or libraries designed for schema validation.

Can I validate JSON from a URL?

Our validator supports pasting JSON directly and uploading files. You can also copy JSON from a URL and paste it into the validator for quick validation.

About JSON Syntax Validation

JSON syntax validation is the process of checking whether a JSON document conforms to the JSON specification and contains valid syntax. Our JSON validator not only checks for syntax errors but also provides detailed error messages with line numbers to help you understand and fix issues quickly.

In addition to basic JSON syntax validation, our JSON linter can automatically correct invalid JSON by fixing many common JSON formatting errors, saving you time and reducing frustration when working with JSON data from APIs or configuration files.

Validation Features

  • Real-time JSON syntax checking with line-by-line error reporting
  • Support for multiple JSON specifications (RFC 8259, RFC 7159, RFC 4627)
  • JSON syntax fixer that automatically corrects common JSON errors
  • Detailed error messages with suggestions and line numbers
  • JSON format checker for nested JSON structures
  • JSON object validator for schema validation
  • File upload support for large JSON files
  • 100% client-side processing for complete privacy