What Is Live JSON Validation?
Live validation means your JSON is checked for syntax errors as you type, without needing to click a button. JSONKit validates your input on every keystroke using the browser's native JSON.parse() engine — the same parser used by JavaScript itself.
What Errors Does It Catch?
Live validation catches every JSON syntax error. The most common ones are:
- Missing comma between two properties or array items
- Trailing comma after the last property — valid in JavaScript but not in JSON
- Single quotes used instead of double quotes around strings or keys
- Unquoted keys — in JSON every key must be a string in double quotes
- Unclosed bracket or brace — a missing ] or } at the end
- Invalid value — undefined, NaN and Infinity are not valid JSON values, use null instead
- Comments — JSON does not support // or block comments
How to Read the Error Message
When JSONKit finds an error, a red bar appears at the bottom of the input panel. The message tells you three things: what went wrong, which line it is on, and which column on that line.
For example: Unexpected token on line 6, col 18 means the parser found something it did not expect at character 18 of line 6. Count to that position in your input and you will find the problem.
Why Line and Column Numbers Matter
Without line and column information you would have to scan the entire document to find the error. In a 500-line JSON file this could take minutes. With exact coordinates you jump straight to the problem.
Live Validation vs Click-to-Validate
Some JSON tools only validate when you press a button. JSONKit validates continuously. The output panel only updates once the JSON becomes valid, so you always see the last known-good state on the right while editing on the left.
Where Live Validation Runs in JSONKit
Live validation runs in the JSON Formatter, JSON Validator, JSON Minifier, and all converter pages. The JSON Validator page gives you the most detail — it shows a large green or red status card in the output panel with full error information and file size stats when valid.