Free Online JSON Validator & Syntax Checker
Paste your JSON and instantly check if it's valid. Find syntax errors with precise line and column numbers. Fix malformed JSON quickly — no uploads, no servers, 100% private.
Valid JSON — no syntax errors found
Processed entirely in your browser · No data uploaded
How to Use the JSON Validator
Paste Your JSON
Copy your JSON data from any source — API responses, config files, or code. Paste it into the input editor.
Auto-Validate Instantly
The tool validates your JSON in real-time. A green checkmark means valid JSON. Errors are highlighted with line numbers and descriptions.
Fix & Copy
Use the error details to fix syntax issues in your code. Copy the validated JSON or download it for use in your project.
Powerful JSON Validation Features
Everything you need to validate JSON data quickly and accurately — all in one free tool.
Real-Time Validation
JSON validity is checked instantly as you type or paste. See a clear valid/invalid status at a glance.
Precise Error Location
Errors show exact line and column numbers so you know exactly where to look. No more guessing.
Syntax Highlighting
Color-coded keys, strings, numbers, and booleans make it easy to spot structural issues visually.
Error Descriptions
Each validation error includes a clear description explaining what went wrong and how to fix it.
Copy to Clipboard
Copy validated JSON to your clipboard with one click. Ready to paste into your editor or documentation.
Download as File
Download valid JSON as a .json file. Perfect for exporting configurations and API responses.
Character & Line Count
Track your JSON size with live character and line counts displayed at the bottom of the editor.
Multiple Indent Styles
Choose between 2-space, 4-space, or 1-space indentation to match your project's coding style.
Why Use Our JSON Validator
The fastest way to validate JSON online. No sign-up, no limits, no data leaving your browser.
100% Free
No hidden fees, no usage limits. Validate as much JSON as you need, as often as you want.
Privacy First
Your JSON data never leaves your browser. Everything is processed locally — no server uploads, no logging.
Real-Time Feedback
Get instant validation results as you type. No submit buttons, no waiting — just paste and see.
Developer-Focused
Built by developers for developers. Precise error messages and line numbers speed up debugging.
Key Highlights
- No sign-up or registration required
- All processing happens in your browser — zero server uploads
- Validates JSON, JSONP, and partial JSON snippets
- Handles large JSON files efficiently (up to 10MB)
- Works on desktop, tablet, and mobile devices
- Clear, actionable error messages with line numbers
Frequently asked questions
What is a JSON validator?
A JSON validator checks whether your JSON data follows the correct syntax rules defined by the JSON specification. It verifies proper use of brackets, commas, quotes, colons, and data types, and reports any errors with precise location information.
Is this JSON validator really free?
Yes, completely free. There are no hidden charges, no usage limits, and no premium features. Use it as much as you need, whenever you need it.
Is my JSON data secure?
Absolutely. All JSON validation happens entirely in your browser using JavaScript. Your data is never sent to any server, stored, or logged. Your sensitive API keys and configuration data stay completely private.
What types of JSON errors can this detect?
The validator detects all common JSON syntax errors including: missing or extra commas, unclosed brackets or braces, missing quotes around keys, trailing commas, invalid data types, unexpected tokens, and malformed strings.
What's the difference between validating and formatting?
Validating checks whether your JSON follows proper syntax rules and reports errors. Formatting (or pretty-printing) rearranges your JSON with proper indentation and line breaks. Our validator does both — it formats valid JSON and reports errors if the JSON is malformed.
Can I validate minified JSON?
Yes! Minified JSON is fully supported. Paste compressed JSON without any whitespace, and the validator will check it for syntax errors while also formatting it into a readable structure.
Do I need to install anything?
No installation required. The JSON validator works entirely in your web browser. Just open the page and paste your JSON. No downloads, no plugins, no setup.
What size JSON can I validate?
Our tool can validate JSON data up to approximately 10MB in size. For larger files, your browser may experience performance issues since everything is processed client-side.