Free Online JSON Validator – Check JSON Syntax Instantly
Validate JSON syntax with precise error messages and line numbers.
Hey there! Whether you are debugging APIs, fixing config files, or working with data, one small mistake in JSON can cause big headaches. Our free JSON Validator helps you catch problems instantly.
Just paste your JSON and the tool checks it in real time. If everything is correct, you will see a clear “Valid JSON!” message. If there is an error, you get an exact line number and column number so you can fix it quickly. Everything runs in your browser – 100% free, private, and no signup needed.
Why Validate JSON Before Using It?
Invalid JSON can break APIs, crash applications, and waste hours of debugging time. A quick validation check helps you catch issues early and saves a lot of frustration.
JSON Validator vs Other Tools
Many tools only tell you “invalid”. Our validator goes further:
- Real-time validation as you type
- Precise error location with line and column numbers
- Clear checklist showing what passed and what failed
- Extra JSON details when valid (depth, nodes, root type)
- One-click auto-fix and formatting
When Should You Use the JSON Validator?
- Before sending data to an API
- When fixing broken configuration files
- While debugging JavaScript or backend code
- Testing JSON from external sources
- Learning or teaching JSON syntax
How to Validate JSON in 3 Simple Steps
- Paste your JSON into the input box on the left.
- The result appears automatically on the right side.
- If invalid, fix the error at the shown line and column. If valid, click “Auto-fix & Format” to clean it up.
Common JSON Errors This Tool Catches
- Missing or extra commas between properties
- Unmatched curly braces { } or square brackets [ ]
- Using single quotes instead of double quotes
- Trailing commas after the last item
- Invalid values like undefined
- Duplicate keys in objects
Standout Features You’ll Use Every Day
- Real-time validation while typing
- Exact line and column error reporting
- Simple pass/fail checklist
- JSON statistics when valid (max depth, total nodes, root type)
- One-click auto-fix and pretty formatting
- Valid and invalid sample buttons for quick testing
- Completely private – nothing leaves your browser
Real Example – Before and After
Invalid JSON Example:
{
"name": "Bad JSON",,
"value": 100
"missing": "comma above"
}
After fixing and using Auto-fix, it becomes clean and valid.
Pro Tips
- Use the “Valid Sample” and “Invalid Sample” buttons to see how the tool works
- Always run validation before sending JSON to an API
- Click Auto-fix after validation to get nicely indented JSON
- Check the depth and node count to understand complexity
Why Developers Love This JSON Validator
- Forever free with no limits or ads
- 100% browser-based and private
- Fast and accurate error reporting
- Simple, clean interface that works on mobile too
- Perfect companion to the Formatter, Beautifier, and Minifier
Ready to Validate Your JSON?
Stop guessing what’s wrong. Get instant, precise feedback and fix errors fast.
→ Validate Your JSON Now – Free & Instant