JSON validator

What this tool does

This validator only checks JSON syntax. It does not evaluate JSON Schema, OpenAPI, or TypeScript types. A document can be valid JSON and still be the wrong shape for your application.

How to use it

1. Paste the candidate JSON.
2. Read the result. Valid documents return a short confirmation.
3. If it fails, use the line and column hint, then repair or reformat.

Privacy

This tool processes files and text locally in your browser. Your content is not uploaded or stored by this site.

ConvertPass does not include your input in analytics, URLs, or error reports. Encoding: UTF-8. Limit: 2 MB (2.00 MB).

Limitations

• This is syntax validation, not schema validation.
• Duplicate keys are accepted by JSON.parse; the last value wins. That is a JavaScript behaviour, not a JSON recommendation.

Example

{"ok": true,}

Invalid JSON. Unexpected token } ... Approximate location: line 1, column 13.

Troubleshooting

It says valid but my app rejects it

Your app likely expects a schema: required keys, enums, or a top-level array. Check the consumer, not only JSON syntax.

FAQ

Is this JSON Schema validation?

No. JSON Schema is a separate contract. This tool only asks whether the text parses as JSON. Schema checking will only be added if it can run locally with documented draft support.

Does it accept NaN or Infinity?

No. Those tokens are not JSON. They appear in some JavaScript object dumps and will fail here.

What about UTF-16 surrogate pairs?

JSON strings may include escaped surrogate pairs. Unpaired escapes should fail. Paste the real file rather than copying from a terminal that mangled encoding.

Why validate locally?

JSON payloads often contain tokens, personal data, or unreleased content. A local validator avoids pasting those into a third-party website that logs input.