Which JSON syntax is valid?

Valid JSON syntax requires specific rules: keys must be strings in double quotes, string values must use double quotes (not single quotes), no trailing commas after the last item, proper bracket and brace matching, and valid data types only (strings, numbers, booleans, null, objects, arrays). Valid example: {"name": "John", "age": 30, "active": true}. Invalid examples include: using single quotes, trailing commas like {"name": "John",}, unquoted keys like {name: "John"}, or undefined values. Arrays must use square brackets with comma-separated values: ["item1", "item2"]. Numbers cannot have leading zeros except for decimals. No comments are allowed in standard JSON. Use our JSON Editor at jsonconsole.com/json-editor to validate your JSON instantly. The editor highlights exactly what makes syntax invalid and suggests corrections, helping you learn proper JSON syntax while ensuring your data is correctly formatted.