JSON Formatter Pro

Auto-detect and format JSON in the browser with syntax highlighting, collapsible trees, search, and themes.

JSON Formatter Pro automatically detects JSON responses in your browser and transforms them into a beautifully formatted, interactive view — right in the tab. No clicking. No copy-pasting into external tools. Just open any JSON API endpoint or .json file and it works instantly. ✦ FEATURES ▸ Auto-Detection Automatically detects pages with application/json content type or raw JSON text. No manual activation needed — just navigate to a JSON URL and the formatter kicks in. ▸ Syntax Highlighting Color-coded display for every data type: Keys (blue), Strings (green), Numbers (orange), Booleans (red), Null (gray italic). ▸ Collapsible Nodes Click the arrow next to any object or array to collapse or expand it. Collapsed nodes show a preview like Object{5} or Array(10) so you always know what's inside. ▸ Collapse All / Expand All One-click buttons in the toolbar to collapse or expand the entire JSON tree. Perfect for getting a high-level overview of large responses. ▸ Line Numbers Every line is numbered for easy reference — simple to discuss specific parts of a JSON response with your team. ▸ Search Type in the search box to instantly highlight matching keys or values across the entire document. A match counter shows how many results were found. ▸ Clickable URLs URLs inside JSON string values are automatically rendered as clickable links that open in a new tab. No more copy-pasting URLs from JSON responses. ▸ Copy to Clipboard Copy the entire formatted JSON with one click. Or double-click any individual value to copy just that value. ▸ Raw / Formatted Toggle Switch between the beautifully formatted view and the raw JSON text with a single click. Useful when you need to copy the raw payload. ▸ Dark & Light Themes Includes both a dark theme and a clean light theme. Automatically follows your system preference, or set it manually from the popup. ▸ JSON Size & Key Count The toolbar displays the file size and total number of keys at a glance — helpful for understanding the scope of a response. ▸ Error Handling If the JSON is malformed, the extension shows a clear error message with line and column information so you can quickly locate the problem. ▸ Large File Protection Files over 10 MB trigger a warning before formatting, giving you the option to view raw or format anyway — preventing accidental tab freezes on huge responses. ▸ On/Off Toggle Easily enable or disable the extension from the popup without uninstalling it. Settings persist across browser sessions. ✦ BUILT FOR DEVELOPERS JSON Formatter Pro is designed for web developers, API engineers, QA testers, and anyone who regularly works with JSON data in the browser. Common use cases: inspecting REST API responses, debugging webhook payloads, reviewing JSON config files, exploring public APIs, and sharing formatted JSON with teammates. ✦ PRIVACY JSON Formatter Pro does not collect, store, or transmit any data. Everything runs locally in your browser. No analytics. No tracking. No network requests. Your data never leaves your machine. ✦ PERMISSIONS Storage — saves your preferences (theme, enabled/disabled) locally on your device. Host permissions (http/https) — required so the content script can detect JSON pages. The extension only activates on pages that contain valid JSON. ✦ KEYBOARD ACCESSIBLE All interactive elements (collapse toggles, buttons, search) are fully keyboard accessible with proper focus indicators and ARIA labels. ✦ OPEN SOURCE JSON Formatter Pro is free and open source. Found a bug or have a feature request? Open an issue on GitHub.