JSON
JSON Validator
Validate JSON before using it in code, APIs, or config files. Errors and previews are produced locally.
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Runs locally in your browser. Your input is not uploaded.
How this tool works
JSON validation checks whether text can be parsed by the standard JSON parser.
When the input is valid, the tool also shows a formatted preview for easier inspection.
Examples
- Check a webhook payload before sharing it with a teammate.
- Validate a package-like config snippet before saving it.
- Validate a multiline payload and use the reported line and column to correct a missing comma.
Common use cases
What validation proves
Validation proves that the text can be parsed as standard JSON. It does not prove that the shape matches an API schema, that required fields are present, or that values are acceptable to your application.
After validation succeeds, the formatted preview helps you inspect nesting and confirm that arrays, objects, and primitive values landed where you expected.
Common syntax issues
- JSON object keys must be quoted with double quotes.
- Strings must use double quotes, not single quotes.
- Trailing commas and comments are invalid in standard JSON.
- Missing commas often cause parser errors near the next property or array item.
Invalid or unsafe assumption
Invalid/failure example
{name: 'Ada'} is a JavaScript-like object, not valid JSON.
Mistakes to avoid
- Confusing syntax validation with schema validation.
- Fixing the final error before the first parser error.
- Allowing comments because a particular editor accepts JSONC.
Limits of this workflow
The validator checks JSON grammar, not required fields or types.
Native parser messages can vary slightly between browser engines.
Local-processing and privacy boundary
Validation uses JSON.parse locally and the private input is never posted by the application.
Practical workflow
- Validate the exact payload bytes.
- Start at the first line and column reported.
- Correct delimiters, quotes, or commas.
- Apply a schema validator separately when a contract exists.
Related guides
Official references
FAQ
Can this validate JSON with comments?
No. Standard JSON does not allow comments, so commented JSON will be reported as invalid.
Does validation upload my data?
No. JSON parsing happens in the browser.
Does valid JSON satisfy an API contract?
Not necessarily. Syntax can be valid while fields, types, or values violate the API schema.