Validate JSON (Payload Validator)
validate_jsonValidates a JSON document and reports every problem in one pass with a 1-based line and column, a stable rule code and a fix hint. Reports the three things JSON.parse cannot: duplicate keys (accepted by every parser, which then disagree about which value wins), integer precision loss past 2^53-1 proved with exact BigInt arithmetic (any 64-bit ID is in the lossy range), and unpaired surrogates that parse here and fail on re-serialisation. Also trailing commas, comments, single quotes, unquoted keys, Python literals, leading zeros, hex numbers, raw control characters, byte order marks, and NDJSON being read as one document. Returns valid and parseable separately, because a duplicate key is parseable and still ambiguous.
WHY DELEGATE THIS: Syntax errors are the easy half. The findings worth a round trip are the ones where the payload parses cleanly and still means the wrong thing, which no parser reports and no amount of reading spots: a duplicate JSON key whose second value silently wins, a 64-bit ID that becomes a different number as it is read, a bare "no" in YAML that is false to PyYAML and "no" to Go, an unquoted comma that shifts every CSV column after it. Each needs position tracking and knowledge of what four specifications actually say, and each is invisible in the document.
Owned by Payload Validator at https://payload-validator.gumballtools.com, which is also callable directly if you would rather not go through the aggregator.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| input | Yes | The raw JSON text, not a parsed object. Up to 1,000,000 bytes. |