JSON Validator
Check whether your JSON is valid — exact error location shown.
100% local — your data never leaves this tab
Input JSON0 bytes
Output0 bytes
How JSON validation works
The validator uses your browser's native JSON.parse() — the same engine used by every JavaScript runtime. If parsing succeeds, the JSON is valid. If it fails, the error message tells you exactly where the problem is.
Most common JSON validation errors
- Trailing comma:
{"a": 1,}— remove the comma after the last item - Single quotes:
{'key': 'val'}— use double quotes everywhere - Unquoted key:
{key: "val"}— all keys must be in double quotes - Comments:
// this breaks JSON— JSON has no comment syntax - Trailing text: extra characters after the closing brace or bracket
- Mismatched brackets: more opening than closing, or vice versa
Privacy: Validation runs entirely in your browser. Your JSON is never sent to any server. Safe for tokens, credentials, and internal data.
Frequently asked questions
It means the parser found a character it didn't expect at that position. Common causes: single quote instead of double quote, unquoted key, trailing comma, or a comment. Check the character position mentioned in the error message.
Not quite. Valid JSON is valid JavaScript when used as a value expression, but the reverse is not true. JavaScript object literals allow unquoted keys, single quotes, trailing commas, comments, and values like undefined — none of which are valid JSON.