JSON Validator & Beautifier
100% Free · Client-Side
Validate, beautify, and minify JSON with detailed error messages. Configurable indentation and tree view.
JSON Editor
What is the JSON Validator & Beautifier?
The JSON Validator parses and validates any JSON string, showing exactly where syntax errors occur. It also beautifies (pretty-prints) valid JSON with consistent indentation for readability, or minifies it to reduce payload size. All processing is done locally in your browser.
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's the difference between JSON and JSON5?
JSON is strict. No comments, no trailing commas, all keys must be quoted. JSON5 is a superset that allows these. This tool validates strict JSON (RFC 8259).
2. Can I validate very large JSON files?
Yes. Processing is done locally in the browser without server uploads. Performance depends on your device's memory and the browser's JavaScript engine.