JSON Formatter & Validator
A JSON formatter is an online tool that automatically formats and beautifies JSON data with proper indentation, making it readable and easier to debug. It validates JSON syntax and highlights errors in real-time.
How to Format JSON Online
- 1
Paste Your JSON
Copy your JSON data and paste it into the input field on the left.
- 2
Click Format or Validate
Click the "Format" button to beautify your JSON, or "Validate" to check for syntax errors.
- 3
Copy the Result
The formatted JSON appears in the output field. Click "Copy" to copy it to your clipboard.
Frequently Asked Questions
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 commonly used for transmitting data between a server and web application.
Why should I format JSON?
Formatting JSON makes it easier to read and debug. Properly indented JSON helps you quickly identify the structure of your data, spot missing brackets or commas, and understand nested objects and arrays.
Is my data safe when using this tool?
Yes, absolutely. All processing happens directly in your browser. Your data is never sent to any server, stored, or transmitted anywhere. The tool works entirely offline once loaded.
What is the difference between formatting and minifying JSON?
Formatting adds whitespace and indentation to make JSON human-readable. Minifying removes all unnecessary whitespace to reduce file size, which is useful for production environments where bandwidth matters.
Common Use Cases
API debugging: Paste raw API responses to inspect structure and spot malformed fields. Formatted JSON makes nested objects and arrays easier to trace.
Config files: Validate JSON in package.json, tsconfig.json, or other config files before committing. Catch trailing commas and missing quotes early.
Data migration: Minify large JSON payloads before inserting into databases or sending over the wire. Format outputs for log inspection.
CI/CD pipelines: Validate JSON schema or config before deployment. Our validator helps catch syntax errors that would otherwise fail in production.
CLI Alternatives
For terminal workflows, jq is the standard JSON processor. Examples:
$ jq . config.json
$ jq -c . input.json
$ jq empty < config.json && echo "Valid"
Python: json.loads() for parse, json.dumps(obj, indent=2) for pretty output. Node: JSON.parse() and JSON.stringify(obj, null, 2).
Edge Cases and Common Mistakes
- Trailing commas: JSON does not allow trailing commas.
{"a": 1,}is invalid. Our tool can auto-repair some cases. - Unquoted keys: Keys must be double-quoted.
{key: "value"}is invalid JavaScript but not valid JSON. - Single quotes: JSON requires double quotes for strings. Single quotes are not allowed.
- BOM and encoding: A leading UTF-8 BOM can cause parse failures. Strip it if you copy from editors that add it.
- Deep nesting: Very deeply nested structures can blow the call stack in some parsers. Consider flattening if you hit limits.
Security Notes
Never blindly pass untrusted JSON to eval() or JSON.parse() in contexts where prototype pollution could matter. Use a schema validator (e.g. JSON Schema, Zod) for input from users or external APIs. Our formatter is for readability and debugging, not input sanitization. Do not use it as a security layer.