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Validate, format, and debug JSON instantly with detailed syntax errors, line numbers, structure analysis, and beautified output.
This online JSON validator helps developers validate JSON online, debug invalid JSON payloads, format structured data, and identify syntax issues instantly. The built-in JSON parser checks for missing commas, invalid quotes, malformed objects, trailing commas, and other common JSON parse errors.
Whether you are debugging REST API responses, editing configuration files, or working with frontend applications, this JSON syntax checker makes it easier to validate and format JSON data safely.
Validating JSON before using it in your application helps prevent runtime errors, API failures, broken configurations, and malformed data imports. A proper JSON lint and validator workflow improves debugging and data reliability.
REST API response validation
package.json debugging
tsconfig.json verification
Firebase configuration checks
JSON file formatting before import
Testing webhook payloads
Debugging frontend applications
Cleaning copied JSON data
Remove commas after the final property in an object or the final item in an array.
JSON strings and property names must use double quotes, not single quotes.
Every object key must be wrapped in double quotes, even if it looks like a JavaScript identifier.
Add commas between object properties and array items so the parser can separate values.
Remove // and /* */ comments before using JSON in APIs, config files, or data imports.
Use true, false, and null in lowercase. Values such as True, None, undefined, and NaN are invalid.
Invalid JSON
{
name: 'John',
age: 30,
}Valid JSON
{
"name": "John",
"age": 30
}JSON parse errors happen when the structure does not follow official JSON syntax rules. Common causes include missing commas, invalid quotes, trailing commas, comments, malformed arrays, and invalid object structures.
This JSON error checker highlights the exact line and column where validation fails, helping developers quickly debug invalid JSON payloads and API responses.
Yes. You can validate, format, paste, upload, and reset JSON directly in your browser without creating an account.
No. Validation runs client-side in your browser, so the JSON you paste or upload stays on your device.
Yes. After entering valid JSON, use the formatter button in the editor toolbar to beautify it with indentation.
JSON is stricter than JavaScript object syntax. JSON does not allow comments, trailing commas, single-quoted strings, or unquoted keys.