Free Online JSON Validator

Common JSON Errors and How to Fix Them

Missing comma between properties

// Wrong
{"name": "Evans" "role": "developer"}

// Correct
{"name": "Evans", "role": "developer"}

Trailing comma (not valid in JSON)

// Wrong
{"name": "Evans", "role": "developer",}

// Correct
{"name": "Evans", "role": "developer"}

Single quotes instead of double quotes

// Wrong
{'name': 'Evans'}

// Correct
{"name": "Evans"}

Unquoted key

// Wrong
{name: "Evans"}

// Correct
{"name": "Evans"}

JSON vs JSONC — What Is the Difference?

Standard JSON does not support comments. JSONC (JSON with Comments) is a superset used in configuration files like VS Code's settings.json. If your JSON contains // or /* */ comments, it is JSONC — strip the comments before validating as standard JSON.

Frequently Asked Questions

Why is my JSON invalid?

The most common causes are trailing commas, single quotes, unquoted keys, and mismatched brackets. ClickSail shows the exact line and character where the error occurs.

Does JSON allow comments?

No. Standard JSON does not allow comments. Use JSONC or strip comments before validation.

Does it validate nested JSON?

Yes. The validator handles deeply nested objects and arrays.

Is it free?

Yes, completely free.

Is my JSON stored?

No. All validation runs in your browser.