JSON Validator & Syntax Checker
Validate your JSON data against RFC 8259 standards, catch syntax errors instantly, and pin-point missing brackets or quotes.
What is a JSON Validator?
A JSON Validator checks whether your JSON string follows the official RFC 8259 data interchange format specification.
Even a small syntax issue—such as a missing double quote, a trailing comma, or an unescaped special character—can cause a JSON parser to fail. The validator provides the exact error position, line number, and a suggested fix.
How to Validate JSON Online?
Paste String
Paste your JSON payload or API response into the left text area.
Click Validate
Click Validate JSON. The tool tests the input with a real-time JavaScript parser.
Read Diagnostics
Review the success report for valid JSON, or the exact error line and character position for invalid JSON.
Strict JSON Rules (RFC 8259 Standard)
| Rule Category | Valid Syntax Example | Invalid Syntax Example |
|---|---|---|
| String Quotes | "name": "John" (Double quotes required) |
'name': 'John' (Single quotes are not allowed) |
| Trailing Commas | [1, 2, 3] |
[1, 2, 3,] (A comma after the last item is invalid) |
| Array Key-Value Pairs | [{"key": "val"}] (Object inside Array) |
["a", "b", "key": "val"] (A direct key-value pair in an array is invalid) |
| Object Keys | {"age": 25} |
{age: 25} (Unquoted keys are not allowed) |
Frequently Asked Questions (FAQ)
JSON.parse() exception stack and position offset to calculate the input character's line and column numbers.