Detailed Error Messages
Get precise error locations with line and column numbers so you can fix JSON syntax issues quickly.
JSON Validator Online
Lines —Chars —Size ——
Paste JSON data on the left to validate
Validate JSON Online
The JSON Validator instantly checks your JSON syntax and reports detailed error messages with line and column numbers. Detects missing commas, unmatched brackets, trailing commas, and all other JSON syntax errors. 100% private — all processing happens in your browser.
Key Features
Instant Validation
Validates your JSON in real time as you paste or upload your data. No waiting, no page reloads.
100% Private
All processing runs entirely in your browser. No data is ever sent to a server. Your JSON stays private.
How to Use
1
Paste or Upload JSONPaste your JSON into the editor or upload a .json file.
2
Click ValidateHit the Validate button to check your JSON syntax for errors.
3
Review ResultsSee if your JSON is valid, or get detailed error messages with line and column numbers to fix issues.
Common Use Cases
API Response Debugging
Validate JSON responses from REST and GraphQL APIs to ensure they are well-formed before processing.
Config File Validation
Check package.json, tsconfig.json, and other config files for syntax errors before deployment.
Data Import Checks
Validate JSON data files before importing into databases to prevent failed ingestion from syntax errors.
Code Review
Quickly validate JSON snippets during code reviews to catch syntax issues before they reach production.
Frequently Asked Questions
How do I validate JSON?
Paste your JSON data or upload a JSON file. The validator instantly checks the syntax and reports whether the JSON is valid, with detailed error messages if any issues are found.
What errors does the JSON validator detect?
The validator detects all JSON syntax errors including missing commas, unmatched brackets or braces, invalid strings, trailing commas, single quotes instead of double quotes, and other common mistakes.
Is this JSON validator free?
Yes! Online Data Tools JSON Validator is completely free with no sign-up, no ads, and no data limits.
Is my JSON data safe when validating?
Absolutely. All validation happens in your browser using JavaScript. No data is ever sent to any server.