JSON Formatter
Format, validate, and beautify JSON instantly. Spot syntax errors with line numbers.
Output
What is JSON?
JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. It is the most widely used format for APIs, configuration files, and data storage on the web.
Common JSON syntax errors
- Trailing commas after the last item in an array or object
- Single quotes instead of double quotes around keys or strings
- Missing quotes around property names
- Comments (JSON does not support comments)
- Unescaped special characters in strings
- Using
undefinedorNaN(not valid JSON values)
How to use the JSON formatter
- Paste your JSON into the input box (or click "Load sample")
- Click "Format / Beautify" to pretty-print with indentation
- Click "Minify" to compress into a single line
- If your JSON has errors, the tool highlights the issue
- Copy the result and use it in your project
Frequently Asked Questions
What is the difference between JSON and a JavaScript object?
JSON is a string format for data interchange. JavaScript objects are in-memory data structures. JSON requires double quotes around all keys and string values, does not support functions, and does not allow trailing commas or comments.
Is this tool safe for sensitive data?
Yes. All formatting and validation happens entirely in your browser. Your JSON data is never sent to any server — it stays on your device.
Can I format large JSON files?
This tool can handle JSON files up to several megabytes in size. For extremely large files (100MB+), consider using a desktop tool like jq for better performance.