JSON validator
What this is
jsonlint.com is a parse-or-fail box. This validator is that plus the errors people actually paste: object literals copied from JavaScript, Python True/None, and duplicate keys that JSON.parse silently collapses. The engine message (Unexpected token, Unexpected end of JSON input) is mapped to a line and column in the gutter. Duplicate keys are a separate warning — V8 keeps the last value, which is a parser-differential risk.
Open the formatter — paste stays in this tab.
FAQ
- Trailing commas?
- Legal in JavaScript, illegal in JSON. Click Repair, or delete the comma before } or ].
- Is a number like 01 valid?
- No. JSON forbids leading zeros. JSON.parse rejects them. Repair does not invent a number; fix the source.