JSON Validator

What is a JSON validator?

A JSON validator checks that text is well formed JSON: braces and brackets that match, keys in double quotes, no trailing commas, and strings that escape their special characters. That is a syntax check. It does not tell you whether the document means what you hoped.

Paste JSON and this tool tells you whether it is valid and, if not, where it breaks.

How to use the JSON validator

JSON

The document to check. There is no schema field on this page.

Valid

A valid document comes back with valid set to true.

Invalid

The result carries the error, the line and column of the first problem (both counted from 1), and a snippet with a caret under the spot.

• Duplicate object keys count as invalid, even though the RFC permits them. Most parsers keep the last value and hide the duplicate.

Why validate JSON before you send it

A log line that looks like JSON can still be missing a comma on line 40. Feed it to a service and you get a 400 from somewhere else, with nothing pointing at your paste. Here you get the line, the column and a caret.

Trailing commas, single quotes and bare keys are common when people write JSON by hand or copy it out of JavaScript. None of those are JSON. Catching them here is cheaper than catching them in production.

JSON validator alternatives

JSON Formatter and Minifier uses the same parser and also refuses invalid input, then gives you pretty or compact text when the JSON is valid. Use it when you wanted formatted output rather than a verdict. For YAML, use YAML Formatter and Validator.

JSON Schema validation is a different job: checking types and constraints against a schema document. This page does not do that. jq, Python's json.loads and editor linters cover the same syntax check locally.

Things to know about JSON validation

The grammar is RFC 8259. Comments are not allowed, and neither are NaN or Infinity. A UTF-8 byte order mark at the start of the text is a frequent copy and paste surprise.