Prettify, minify, and validate JSON. Syntax highlighting with error detection.
Format and validate JSON with syntax highlighting, error detection, and path navigation. Prettify for readability, minify for production. Powered by Prism.js. Pure JavaScript.
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No. Formatting, validation and minifying all run in your browser using JavaScript — nothing leaves your machine. That matters because JSON payloads often contain API keys, tokens or customer records, and pasting those into a tool that uploads them is a genuine security risk. You can even work offline once the page has loaded.
The usual culprits are a trailing comma after the last item, single quotes instead of double quotes, unquoted keys, or a stray comment — all legal in JavaScript but invalid in strict JSON. The error message points at the character where parsing broke, which is typically just after the real mistake.
Prettify while you are reading or debugging — indentation makes structure obvious. Minify for anything you ship: config files, API responses and embedded payloads, where stripping whitespace can cut size by 10–30% and speed up transfers. The data is identical either way, only the formatting differs.
Yes, JSON Formatter & Validator is completely free. No signup, no account, and no watermark on outputs. A Pro tier is available for 100 AI ops/day and larger file sizes.
JSON Formatter & Validator runs entirely in your browser. Your file is never uploaded — it is read, processed and saved locally, so it never reaches our servers or anyone else's. You can disconnect from the internet after the page loads and it still works.
What it does: Parses your JSON using the browser's native JSON.parse() and reformats it with JSON.stringify(). If parsing fails, the exact syntax error is shown so you can locate and fix it.
Prettify vs Minify: Prettify adds indentation and line breaks for human readability — great for debugging API responses. Minify removes all whitespace to reduce payload size for production APIs and configuration files.
Privacy: Your JSON is never sent to any server. All processing happens locally in your browser.