JSON Validator
The JSON Validator checks whether your JSON data conforms to the RFC 8259 specification. It identifies syntax errors, structural problems, and common mistakes like trailing commas, missing quotes, unescaped characters, and mismatched brackets. The validator provides detailed error messages with line and column numbers, making it easy to find and fix issues. This tool is essential for debugging API responses, configuration files, and any JSON data exchange between systems.
Formula
Valid JSON rules:
1. Keys must be in double quotes
2. String values must be in double quotes
3. No trailing commas
4. No comments
5. Must be object {} or array []
6. Booleans: true/false (lowercase)
7. null (not NULL or None) Example
Valid: {"name": "John", "age": 30} Invalid (trailing comma): {"name": "John", "age": 30,} Error: Unexpected comma at line 1, column 26 Invalid (single quotes): {'name': 'John'} Error: Expected property name in double quotes
How to Use
- Paste your JSON into the input field
- The validator checks syntax in real time
- If valid, you see a success message
- If invalid, the error message shows the line and column
- Fix the error and re-validate until valid
Frequently Asked Questions
What makes JSON invalid?
Common causes: trailing commas, single quotes instead of double quotes, unquoted keys, comments (not allowed in JSON), unescaped control characters, and missing or extra brackets/braces. The validator pinpoints the exact location of each error.
Does this validator follow the official JSON standard?
Yes, it validates against RFC 8259, the official JSON specification. This is the same standard used by all major programming languages and API frameworks.
What is the maximum JSON size I can validate?
Most browsers can handle JSON files up to 50-100MB. For very large files, performance may degrade. For production use with huge files, consider using a streaming parser in Node.js or Python.
Can I validate JSON with comments?
Standard JSON does not allow comments. If your JSON has comments, it is JSONC, not JSON. Use a JSONC validator or remove comments before validating. VS Code settings.json is a common example of JSONC.
How is JSON validation different from JSON schema validation?
JSON validation checks syntax (is it valid JSON?). JSON Schema validation checks structure (does it match a expected pattern?). This tool does syntax validation. For schema validation, use tools like ajv or jsonschema.