JSON Validator

Paste JSON to check whether it's valid. If it isn't, you'll see the exact line and column, the offending line highlighted and a plain-English explanation of what to fix.

How to validate JSON

1. Paste your JSON into the box — it's checked as you type.
2. A green ✓ means it's valid. Otherwise read the message and the highlighted line; the caret marks the exact character.
3. Click Jump to error to put your cursor on the problem, fix it, and the result updates instantly.

What makes JSON valid

JSON is defined by RFC 8259 and is much stricter than JavaScript. A document is valid when:

• It contains exactly one top-level value — usually an object {…} or array […].
• Every property name is a double-quoted string, followed by a colon.
• Strings use double quotes and escape ", \ and control characters (\n, \t, \uXXXX…).
• Numbers have no leading zeros, no leading +, no hex, and are never NaN or Infinity.
• The only literals are lowercase true, false and null.
• There are no trailing commas and no comments, and the file doesn't start with a byte order mark.

Why error messages differ between tools

Every browser's JSON.parse words errors differently — Chrome reports a position, Firefox a line and column, and Safari often no location at all. This validator uses its own strict parser, so you get the same precise line, column and suggestion everywhere. Note that duplicate keys are technically allowed by the spec, but most parsers silently keep only the last one — treat them as a bug.

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