JSON Validator - Check JSON Syntax Online

Validate JSON syntax instantly in your browser. Check for errors, view detailed error messages with line numbers. Free, fast, no uploads required.

JSON Input

Drop JSON file here or browse

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Enter JSON and click Validate

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Frequently Asked Questions

This tool validates JSON syntax according to the official JSON specification (RFC 8259). It checks for proper structure, valid data types, correct use of quotes, commas, and brackets.

Yes. All validation happens entirely in your browser using JavaScript. No data is uploaded to any server.

Common errors include: trailing commas, single quotes instead of double quotes, unquoted keys, missing commas between items, and unclosed brackets or braces.

No. This tool identifies errors but doesn't automatically fix them. It provides detailed error messages to help you locate and fix issues manually.

No. This tool validates JSON syntax only. For schema validation (checking data structure and types), you need a dedicated JSON Schema validator.

The validator shows the exact error message from the parser, which usually includes what went wrong and approximately where in the JSON.

Yes. Copy API response JSON and paste it here to verify the syntax is valid before processing it in your code.

The JSON spec allows duplicate keys (last one wins). This validator checks syntax only, not semantic issues like duplicates.

Valid Unicode characters and proper escape sequences (\uXXXX) are supported according to the JSON specification.

Yes. Validation is fast even for large files since it uses the browser's native JSON.parse() function.

JSON Input

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