JSON Validator

Rigorously check JSON data for syntax errors and get precise, actionable error messages showing exactly what is wrong and where. Common errors detected include missing or extra commas, unquoted property keys, single-quoted strings, trailing commas, comments (not allowed in standard JSON), undefined or NaN values, and mismatched brackets. Valid JSON gets a green confirmation with the detected type and a count of top-level keys. Invalid JSON shows the line and character position of the first violation, a highlighted view of the problematic section, and an explanation of what the parser expected. Also checks for duplicate keys that cause unexpected parser behavior. All validation runs in your browser. No account required.