Outliner - HTML Element Inspector
A professional Chrome extension for web developers and designers to inspect and highlight HTML elements with custom outlines. Perfect for visualizing page structure and debugging layouts.
✨ Features
- Element Outlining: Highlight all HTML elements with customizable outlines
- Customizable Styles: Choose from solid, dashed, dotted, or double outline styles
- Color & Width Control: Adjust outline color and thickness to your preference
- Element Information: Hover over elements to see detailed information (tag, ID, classes, dimensions)
- Targeted Selection: Use CSS selectors to highlight specific elements only
- Local File Support: Works on local HTML files and all web pages
- Real-time Updates: Changes apply immediately without page refresh
🚀 Installation
From Chrome Web Store (Recommended)
- Visit the Chrome Web Store
- Search for “Outliner - HTML Element Inspector”
- Click “Add to Chrome”
URL: Outliner - HTML Element Inspector
Manual Installation (Developer Mode)
- Download or clone this repository
- Open Chrome and go to
chrome://extensions/
- Enable “Developer mode” (toggle in top right)
- Click “Load unpacked” and select the extension folder
📖 How to Use
- Enable Outlines: Click the extension icon and press “ENABLE OUTLINES”
- Customize Appearance:
- Change outline color using the color picker
- Adjust outline width with the slider (1-10px)
- Select outline style (solid, dashed, dotted, double)
- Element Information: Enable “Show Element Info” and hover over elements
- Target Specific Elements: Use CSS selectors in the “Target Elements” field (e.g.,
.button, #header, [data-testid])
🎨 Customization Options
Outline Styles
- Solid: Standard continuous line
- Dashed: Broken line pattern
- Dotted: Dotted line pattern
- Double: Two parallel lines
Color Options
- Choose any color using the color picker
- Enter hex color codes manually
- Default color: #00ff9d (neon green)
Width Range
- Adjustable from 1px to 10px
- Real-time preview of changes
🔧 Technical Details
- Manifest Version: 3 (Latest Chrome extension standard)
- Permissions: Minimal permissions required (activeTab, storage)
- Compatibility: Chrome 88+ and Chromium-based browsers
- Performance: Lightweight and fast, no impact on page performance
- Security: No data collection or external requests
🛠️ Development
Project Structure
Outliner/
├── manifest.json # Extension configuration
├── popup.html # Extension popup interface
├── popup.js # Popup functionality
├── content.js # Content script for page interaction
├── background.js # Background service worker
├── icons/ # Extension icons
│ ├── icon16.png
│ ├── icon48.png
│ └── icon128.png
└── README.md
Building for Production
- Ensure all files are properly organized
- Test thoroughly on various websites
- Create a ZIP file of the extension folder
- Submit to Chrome Web Store Developer Dashboard
🐛 Troubleshooting
Common Issues
- Extension not working: Reload the extension in
chrome://extensions/
- No outlines visible: Check if outlines are enabled in the popup
- Settings not saving: Ensure storage permission is granted
- Local files not working: Make sure you’re using
file:// URLs
Browser Compatibility
- ✅ Chrome 88+
- ✅ Edge (Chromium-based)
- ✅ Brave Browser
- ✅ Opera (Chromium-based)
📝 Privacy & Security
- No Data Collection: This extension does not collect or transmit any user data
- Local Storage Only: Settings are stored locally in your browser
- No External Requests: The extension doesn’t make any network requests
- Open Source: Full source code available for transparency
🤝 Contributing
We welcome contributions! Please feel free to:
- Report bugs or issues
- Suggest new features
- Submit pull requests
- Improve documentation
📄 License
This project is licensed under the MIT License - see the LICENSE file for details.
🙏 Acknowledgments
- Built with modern Chrome Extension APIs
- Designed for web developers and designers
- Inspired by browser developer tools
📞 Support
For support, questions, or feature requests:
Made with ❤️ for the web development community