JSON Validator & Beautifier
Validate, beautify, and minify JSON with detailed error messages. Configurable indentation and tree view.
JSON Editor
What is the JSON Validator & Beautifier?
Common JSON Syntax Errors
| Error | Example |
|---|---|
| Trailing comma | {"a": 1,} |
| Single quotes | {'key': 'value'} |
| Unquoted keys | {key: "value"} |
| Undefined/NaN values | {"a": undefined} |
| Comments in JSON | {"a": 1 // comment} |
Common Use Cases
- Validate API responses before processing them in code
- Debug JSON syntax errors from logs, config files, or API payloads
- Beautify minified JSON from network requests (DevTools) for manual inspection
- Minify JSON configuration files before deploying to reduce file size
- Validate
package.json,tsconfig.json, or other configuration files
Frequently Asked Questions
1. What is the difference between JSON and JSON5?
Standard JSON (RFC 8259) is strict: no comments, no trailing commas, and all keys must be double-quoted. JSON5 is a modern superset that allows these and more. This tool validates strictly against the standard JSON specification.
2. Can I validate very large JSON files?
Yes. All processing is done locally in your browser using JavaScript. While there is no hard limit, performance depends on your device's memory. For extremely large files (50MB+), some browsers might experience a slight delay during beautification.
3. Is my JSON data sent to a server?
No. Your data never leaves your computer. We do not use any tracking or logging that captures your input, making it safe to validate sensitive config files or API keys locally.
4. Why is my valid JSON being marked as invalid?
Common issues include invisible characters (like non-breaking spaces), single quotes instead of double quotes, or trailing commas at the end of objects/arrays. Our validator points to the exact line and character where the error was detected.