What is JSON Validator?
JSON Validator checks your JSON syntax and structure, providing detailed error messages with line numbers. Perfect for debugging API responses and configuration files.
Valid JSON is critical for APIs, databases, and data exchange. A single syntax error can break your entire application. Our validator instantly checks JSON structure, reports errors with exact locations, and provides helpful statistics about your data.
How to Validate JSON Online
- Paste JSON: Copy JSON from any source - API responses, config files, or code
- Instant validation: See results in real-time as you type or click "Validate"
- Error details: Get exact line and column numbers for syntax errors
- View statistics: See total keys, values, nesting depth, and file size
- Fix and revalidate: Make changes and validate again until JSON is error-free
Why Validate JSON?
Prevent Production Errors
Catch syntax errors before deploying to production. Invalid JSON in configuration files can crash servers, break CI/CD pipelines, or cause runtime errors that are hard to debug.
Debug API Integration
When consuming third-party APIs, validate responses to ensure they match expected formats. Spot missing fields, incorrect types, or malformed data before it breaks your application.
Verify Configuration Files
package.json, tsconfig.json, and other config files must be valid JSON. One misplaced comma can prevent npm installs or break your build process. Validate before committing.
Data Quality Checks
When exporting data from databases or transforming data formats, validation ensures integrity. Check that JSON exports are well-formed before importing to other systems.
Key Features
- Real-time validation: Instant feedback as you type with 300ms debounce
- Error location: Precise line and column numbers for syntax errors
- Error descriptions: Helpful messages explaining what's wrong
- JSON statistics: Total keys, values, max depth, and file size
- Visual status: Clear ✓ Valid or ✗ Invalid indicators
- Copy validated JSON: Copy error-free JSON for use in code
- Client-side only: Your data never touches our servers
- Fast performance: Validates large files (100KB+) instantly
Common JSON Validation Errors
- Unexpected token: Usually means a missing comma, bracket, or quote
- Unexpected end of JSON: Missing closing bracket or brace at end of file
- Invalid character: Special characters that need escaping (quotes, backslashes)
- Property names must be strings: Keys must be in double quotes
- Trailing comma: JSON doesn't allow commas after last array/object item
- Duplicate keys: Object keys must be unique within same level
JSON Validation Best Practices
Use a linter in your IDE: Tools like ESLint, VS Code's built-in validator, and Prettier catch JSON errors as you code. Our validator is perfect for quick checks when copying JSON from external sources.
Validate before committing: Add JSON validation to your pre-commit hooks using tools like Husky. This prevents invalid config files from breaking builds for your team.
Test API responses: When developing APIs, validate response formats match your documentation. Use our validator to check actual API output against expected schema.
Related Tools
After validating your JSON, you might need: