JSON Formatter — Free Online JSON Beautifier & Validator

formatjson.now is a free online JSON formatter, JSON beautifier, and JSON validator that works instantly in your browser. Paste any JSON — clean, minified, or broken — and get back a properly indented, human-readable result in milliseconds. No installation, no sign-up, no server. Just paste and format.

Works on Windows, Mac, and Linux across all modern browsers — Chrome, Firefox, Safari, and Edge. 95% of APIs use JSON to transfer data between client and server — this tool is built for developers who work with that data every day.

JSON Formatter & Beautifier

The JSON formatter takes raw or minified JSON and outputs it with consistent 2-space indentation and syntax highlighting, making it easy to read and navigate. Use it as a JSON beautifier, a JSON pretty printer, or a JSON viewer — all in one place. Your input is saved to localStorage and restored automatically when you return, making it a handy online alternative to Notepad++, Sublime, or VS Code for quick JSON inspection.

JSON Validator

The built-in JSON validator checks your JSON against the official JSON specification (RFC 8259) and reports any parse errors with exact line number, column, and a code snippet — so it's fast to find and fix the problem. This JSON lint runs entirely in your browser; no data is ever sent to a server.

• · Exact error location — line number, column, and snippet
• · Standards-compliant — validates against RFC 8259
• · Works offline after first load — no network requests needed for your data
• · No software to install — runs in any modern browser

JSON Auto-Fixer — Fix Broken JSON Automatically

The JSON auto-fixer detects and corrects common mistakes before parsing. It handles JSON copied from JavaScript source, Python dicts, log output, and other non-standard formats that are close to valid JSON but not quite right. Each fix is logged — click the "auto fix applied" badge to see exactly what changed, line by line.

• · Trailing commas — ,} or ,]
• · Consecutive commas — ,, or , ,
• · Single-quoted strings — 'value'
• · Unquoted object keys — {key: value}
• · JavaScript comments — // and /* */
• · Capitalized booleans — True / False / Null
• · Unsupported JS types — undefined / NaN / Infinity → null
• · Leading zeros on numbers — 02 → 2
• · Missing commas between adjacent values
• · Node.js console placeholders — [Object] / [Array]

Frequently Asked Questions