JSON Validator

Check whether a JSON document is syntactically valid and get precise error messages that point to the exact location of any problem.

JSON Validator

Validate JSON syntax and get detailed structure analysis with helpful error messages.

JSON Input

Validation Results

About JSON Validation

JSON validation checks syntax correctness and provides detailed structure analysis.

What you'll get:

Syntax validation: Detailed error messages with line numbers
Structure analysis: Object/array breakdown
Size metrics: Character count and byte size
Type counting: Data type distribution

Perfect for: API response validation, debugging malformed JSON, data analysis.

What is JSON Validation?

JSON validation is the process of verifying that a string conforms to the JSON specification (RFC 8259). A valid JSON document must have properly quoted keys, correctly escaped special characters, balanced brackets and braces, and no trailing commas. A validator parses the input and reports any deviations so you can fix them before the data reaches your application.

Common Use Cases

Pre-flight Checks: Validate request bodies before sending them to an API endpoint to avoid unnecessary network round-trips.

Webhook Debugging: Confirm that an incoming webhook payload is well-formed before processing it in your handler.

CI/CD Pipelines: Catch malformed JSON in configuration files or fixture data early in the build process.

Third-party Data: Validate data received from external services that may not always return well-formed JSON.

Tips

Common mistakes include trailing commas after the last item in an object or array, and single-quoted strings instead of double-quoted ones.

After fixing a syntax error, re-run the validator — there may be additional errors that were masked by the first one.

JSON validation only checks syntax. Use a JSON Schema validator for structural and type-level checks.