JSON Formatter & Validator
Format, beautify, minify, and validate JSON data with syntax highlighting and error detection.
About JSON Formatter & Validator
A JSON formatter and validator is an essential developer tool that takes raw, minified, or messy JSON data and formats it with proper indentation, syntax highlighting, and structure visualization. It also validates JSON syntax and highlights errors with line numbers and descriptions. JSON (JavaScript Object Notation) is the most widely used data interchange format on the web, used by virtually every API, configuration file, and data storage system.
How to Use
Paste your JSON data into the input area or type it directly. The tool automatically formats and validates the JSON in real-time. If there are syntax errors, they are highlighted with specific error messages and line positions. You can choose indentation size (2 or 4 spaces), toggle between formatted and minified output, and copy the result to clipboard. The tree view shows the structure visually.
Formula / Key Equations
JSON follows key-value pair syntax: {"key": "value"}. Valid value types: string, number, boolean, null, object {}, array []. Keys must be strings in double quotes. Trailing commas are not allowed in standard JSON. Comments are not supported in standard JSON (though some parsers accept them).
Common Use Cases
Debugging API responses that come as minified JSON. Formatting configuration files (package.json, tsconfig.json, etc.). Validating JSON data before submitting to an API. Comparing JSON structures between two datasets. Learning JSON structure by examining formatted output. Converting between formatted and minified JSON for production vs development use.
Limitations
The validator checks standard JSON (RFC 8259) syntax. It does not validate against a JSON Schema — it only checks structural syntax validity. Very large JSON files (10MB+) may cause browser slowdown. JSON with circular references cannot be processed. JSON5 or other extended JSON formats are not supported.
Frequently Asked Questions
What is the difference between JSON and JSON5?
JSON5 is an extension of JSON that allows trailing commas, single-quoted strings, multi-line strings, comments, and unquoted keys. Standard JSON (RFC 8259) does not allow any of these. Our validator checks standard JSON only.
Why does my JSON have a syntax error?
Common JSON errors include: missing quotes around keys or string values, trailing commas after the last item, single quotes instead of double quotes, unescaped control characters, and comments (not allowed in standard JSON). Our validator highlights the exact position and type of error.
What is minified JSON?
Minified JSON has all unnecessary whitespace removed to reduce file size for faster transmission over networks. This is standard for API responses and production data. Our formatter reverses this by adding proper indentation back for readability.
How do I validate JSON against a schema?
Our tool validates JSON syntax only. To validate against a JSON Schema (which defines the expected structure, types, and constraints), use a dedicated JSON Schema validator like Ajv for JavaScript or jsonschema for Python.
Is my JSON data secure in this tool?
Yes. All JSON formatting and validation happens entirely in your browser. Your data is never sent to any server. When you close the page, the data is completely gone. This makes it safe to format sensitive API responses, configuration files, or any JSON data.
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