JSON Validator

Paste JSON and it is checked as you type. Errors are pinned to the exact line and column with a plain-English reason and a fix tip, and common mistakes such as trailing commas, single quotes and comments can be repaired in one click.

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How to use the JSON Validator

1. Paste or type your JSON in the editor, or upload a .json file. It is validated automatically.
2. Read the result. A green bar means valid JSON. A red bar shows the line, column and reason, and the error line is highlighted.
3. Follow the fix tip or press Auto-fix to repair common mistakes like trailing commas, single quotes and comments.
4. Press Go to error to jump the cursor straight to the problem.
5. Format or minify valid JSON, then copy or download it.

JSON error messages explained

The JSON syntax rules in one minute

JSON (RFC 8259 / ECMA-404) has six value types: object {"key": value}, array [value, value], string in double quotes, number (decimal, optional minus, fraction and exponent, no leading zeros), and the literals true, false and null. Keys are always double-quoted strings. Items are separated by commas with no comma after the last one. Whitespace between tokens is ignored, but there are no comments.

Inside a string, a double quote, a backslash and control characters such as line breaks must be escaped: \", \\, \n, \t, or \u0041 for any character by its code.

Tips for finding the real mistake

• A parser stops at the first problem, so the reported position is where it noticed the error. A missing comma or quote is often at the end of the previous line.
• "Unexpected end of input" means a bracket or string was never closed. The message names the bracket and the line where it was opened.
• Copying from documents and chat apps can turn straight quotes into curly “smart” quotes, which JSON does not accept.
• Large integers such as IDs over 9,007,199,254,740,991 are valid JSON, but JavaScript reads them with rounding. Store them as strings if exact values matter.

Frequently asked questions

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