Dev
JSON Validator
Input
Output
Run process to generate output.
Frequently Asked Questions
What does the JSON validator check?
Syntax validation ensures the JSON is well-formed per RFC 8259: all strings are double-quoted, keys are strings, values are string/number/boolean/null/array/object, no trailing commas, no comments, proper nesting of {} and []. This tool reports the exact line and character of any syntax error.
What are the most common JSON syntax errors?
1) Trailing comma after last item: {"a":1,} (illegal). 2) Single-quoted strings: {'key':'value'} (must be double quotes). 3) Unquoted keys: {key: 'value'}. 4) JavaScript comments (// or /* */). 5) undefined values (not a JSON type). 6) Mismatched braces or brackets.
What is the difference between JSON and JSONC?
JSON (RFC 8259) does not allow comments. JSONC (JSON with Comments) is a non-standard extension used in VS Code configuration files (.vscode/settings.json). JSONC allows // and /* */ comments. Standard JSON parsers reject JSONC. Use a dedicated JSONC parser for those files.