JSON Validator
Validate JSON, see exactly where and why it is broken, then format or minify it.
About JSON Validation
JSON (JavaScript Object Notation) is a strict text format: one misplaced comma or quote makes a whole document unreadable to APIs, config loaders and databases. This validator follows the JSON standard (RFC 8259) exactly and tells you the line, the column and the most likely fix.
Mistakes it explains
- Trailing commas after the last item:
[1, 2,] - Single quotes or unquoted keys:
{'a': 1},{a: 1} - Comments, which JSON does not allow
- Missing commas, and brackets that are never closed
NaN,undefined,TrueandNone- Duplicate keys, shown as warnings because most parsers silently keep only the last value
How to Use
- Paste or type your JSON. It is validated as you type.
- If it is invalid, read the message and click Go to error to jump to the problem.
- Choose an indent and click Format to pretty-print, or Minify to remove all whitespace.
- Tick Sort keys A–Z to order object keys alphabetically, then Copy the result.
Frequently Asked Questions (FAQ)
No. Validation and formatting run entirely in your browser.
No. Numbers and strings are kept exactly as written, so large IDs like 12345678901234567890 and values like 1.10 are not rounded or rewritten.
Standard JSON does not allow them. Some tools accept them (JSON5, JSONC), but most APIs and parsers reject them.
The same key appearing twice in one object is technically allowed, but most parsers keep only the last value, which usually hides a bug.
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