JSON Formatter & Validator
DevMiniTools' JSON Formatter instantly indents, validates, and minifies JSON in your browser, with zero upload and zero signup.
What is JSON Formatter & Validator?
JSON (JavaScript Object Notation) is a lightweight, text-based data format used to exchange structured data between a server and a client, most commonly in REST APIs. A JSON formatter takes minified or messy JSON and re-indents it into a human-readable structure, while a validator checks that the syntax follows the JSON spec (RFC 8259) — catching missing commas, unquoted keys, or trailing commas before they break your code.
How to use JSON Formatter & Validator
- Paste or type your JSON into the input panel.
- The tool auto-formats and validates as you type — no button needed.
- Syntax errors are highlighted inline with the exact line number.
- Click 'Minify' to compress the same JSON for production use.
- Click 'Copy' to copy the formatted or minified output.
JSON Formatter & Validator Example
{"name":"Alex","age":29,"skills":["JS","SQL"]}{
"name": "Alex",
"age": 29,
"skills": ["JS", "SQL"]
}Frequently Asked Questions
Is this JSON formatter free to use?
Yes, completely free with no signup, no usage limits, and no watermarking.
Does my JSON get uploaded to a server?
No. All formatting and validation happens locally in your browser — your data never leaves your device.
Can I minify JSON with this tool?
Yes — the same tool toggles between pretty-print (indented) and minified (single-line, whitespace-stripped) output.
Does it validate against JSON Schema?
It validates syntax correctness (RFC 8259) but not against a custom JSON Schema — for schema validation use our JSON Schema Validator (planned) or a dedicated library.
What's the difference between formatting and minifying JSON?
Formatting adds indentation and line breaks for readability during development; minifying strips all whitespace to reduce payload size for production APIs.