JSON Validator Online
Check if your JSON is syntactically valid. Get exact error positions and plain-English explanations.
What Is a JSON Validator?
A JSON validator checks whether a string conforms to the JSON specification (RFC 8259). When you validate JSON online with our tool, it verifies double-quoted keys, proper comma separation, no trailing commas, no comments, and correct bracket matching — all according to the strict JSON standard.
Our JSON validator goes beyond a simple parse check — it shows you the exact line and column where the error occurs, and explains what went wrong in plain English, not cryptic parser messages. Validate JSON online in seconds, no signup required.
Common JSON Validation Errors
- Unexpected token — a character that doesn't belong at that position
- Trailing comma — a comma before a closing bracket or brace
- Missing comma — two values next to each other without a separator
- Single quotes — keys or values wrapped in single instead of double quotes
- Unquoted keys — object keys without double quotes
- Unexpected end of input — truncated JSON missing closing brackets
Unfamiliar with a term? The JSON Glossary covers every key concept — from RFC 8259 to schema validation.
Validate JSON Online vs. Fix: When to Use Each
Use the JSON validator when you want to check if JSON is valid without changing it — for example, testing an API response or auditing a config file. Use the JSON Fixer when you want to automatically repair all errors and get valid output. Both tools let you validate JSON online instantly in your browser.
Frequently Asked Questions
Yes, completely free with no signup required. Validate unlimited JSON documents.
No. All validation happens in your browser. Your JSON never leaves your device.
Yes — paste your JSON Schema in the Schema tab to validate structure and types, not just syntax.
Other JSON Tools