JSON Validator – Validate JSON Online Free
Validate JSON syntax instantly with our free online JSON Validator. Get precise error messages with line and column numbers to debug and fix malformed JSON fast.
About JSON Validator
A single syntax error can break your entire application. This validator checks your JSON for proper syntax and pinpoints the exact location of any errors, saving you hours of debugging time.
How it works
The tool uses the browser's native JSON.parse to validate your input. When an error occurs, it extracts the position and calculates the exact line and column numbers.
Smart error analysis provides human-readable explanations for common mistakes like missing commas, unquoted strings, or trailing commas that JavaScript doesn't allow in JSON.
When you'd use this
You copied JSON from a log file or API response and need to verify it's valid before using it. Quick validation catches copy-paste errors before they cause problems.
This validator checks syntax only, not semantic correctness. Your JSON might be syntactically valid but still contain wrong data types or missing required fields.
Questions
What JSON syntax errors does it catch?
Missing quotes around keys or strings, trailing commas, unmatched brackets, invalid escape sequences, and unquoted reserved words like true or null.
Can it validate large files?
Yes, but very large files may take a moment to process. For files over 50MB, consider using a command-line validator for better performance.
Does it check JSON Schema?
No, this validates syntax only. For schema validation against a defined structure, use the JSON Schema Validator tool instead.
What's the difference between valid and invalid samples?
Load Valid Sample to see properly formatted JSON. Load Invalid Sample to see common errors and how the validator reports them.
Is my data sent anywhere?
No, validation happens entirely in your browser. Your JSON data never leaves your device, making it safe for sensitive information.