FormatPaste
JSON Validator
Paste JSON to check it. Errors show the line and column; valid JSON is pretty printed.
Output
validatedFree JSON validator
Validate JSON and find syntax errors online
Use this JSON validator to check API responses, config files, fixtures, and request bodies before you ship them. The input is parsed against the strict JSON spec, so trailing commas, comments, and single quotes are reported as errors with their position. Valid JSON is pretty printed on the right so you can review it and copy it.
Strict JSON check
Input is parsed with the same strict rules as JSON.parse in browsers and Node.js.
Error position
Invalid JSON shows the error message with the line and column where parsing stopped.
Formatted when valid
Valid JSON is pretty printed, so the validator doubles as a JSON formatter.
JSON validation example
{"order":1042,"items":[{"sku":"A-1","qty":2}],"paid":false}{
"order": 1042,
"items": [{ "sku": "A-1", "qty": 2 }],
"paid": false
}When to use a JSON validator
Find the exact error
A missing comma or bracket in a large file is hard to spot by eye. The validator reports the line and column where parsing failed, so you can jump straight to the problem.
Check config before deploy
package.json, tsconfig.json, composer.json, and app settings files fail at startup if they are invalid. Validate them before you commit or deploy.
Debug API requests
If an API rejects your request body, paste it here first. A trailing comma or an unescaped quote is a common cause of 400 errors.
Strict JSON vs JSON5 and JSONC
Some tools such as VS Code settings and tsconfig accept comments and trailing commas (JSONC or JSON5). This validator follows strict JSON, so it flags those; remove them if the file must be standard JSON.
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JSON Validator FAQ
How do I validate JSON online?
Paste JSON into the input pane. If it is valid, the status shows Valid JSON and the formatted output appears on the right. If not, the error and its line and column are shown instead.
Is this JSON validator free?
Yes. It is free to use with no sign-up.
Which JSON rules does it check?
The strict JSON standard (RFC 8259): double-quoted keys and strings, no trailing commas, no comments, no single quotes, and no undefined, NaN, or Infinity values.
Why is my JSON invalid when it works in JavaScript?
JavaScript object literals allow things JSON does not: unquoted keys, single quotes, trailing commas, and comments. Code copied from a .js file usually needs those changes before it is valid JSON.
Does it validate against a JSON Schema?
No. It checks JSON syntax only. Checking that the data has the right fields and types needs a JSON Schema validator.
Does it work for large JSON files?
Yes, up to 120,000 characters per paste. Use Open file to load a .json file directly instead of copying it.