JSON Validator
A JSON Validator checks whether a JSON string conforms to the JSON specification (RFC 8259). It reports exact line and column positions of syntax errors such as missing quotes, trailing commas, or mismatched brackets.
What is JSON Validator?
Valid JSON is the foundation of reliable APIs, configuration files, and data pipelines. A single misplaced comma or missing quote causes a parse failure that can crash entire services. This validator runs JSON.parse() inside a try/catch block in your browser, reports the exact character position of every error, and displays a green success badge when the structure is clean. No data is sent anywhere.
Use Cases
- Validating API request payloads before sending them.
- Checking JSON configuration files (ESLint, Babel, tsconfig) before deploying.
- Debugging webhook body parsing failures.
How to Use It
Paste or type your JSON into the editor.
Errors are highlighted in real-time as you type.
Review the error panel for precise line and column numbers.
Fix the reported issues and see the green "Valid JSON" badge appear.
Pros
- Real-time inline error detection.
- Shows exact line and column of the error.
- Privacy-first: no server involved.
Limitations
- Only validates syntax; does not validate data types or schemas.
Best Practices
- Always validate JSON coming from external sources before parsing.
- Use a JSON schema validator (like Ajv) for structural validation beyond syntax.
Common Mistakes to Avoid
- Forgetting that JSON keys must always be double-quoted strings.
- Using JavaScript comments (// or /* */) inside JSON—they are not allowed.
FAQs
What is the difference between JSON Formatter and JSON Validator?
A formatter prettifies valid JSON for readability. A validator checks whether the JSON is syntactically correct and reports errors without modifying the content.
Can I validate JSON with comments (JSONC)?
JSONC is not standard JSON. This tool validates strict JSON per RFC 8259. Strip comments before validating.