A powerful, open-source web annotation extension for Chrome, inspired by Zotero's annotation system. Highlight, underline, and manage annotations with rich-text comments on any webpage.
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Two Annotation Types: Choose between highlighting text with a background color or underlining it.
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Eight Colors: A palette of 8 colors to organize your notes (yellow, red, green, blue, purple, pink, orange, gray).
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Robust & Dynamic: Annotations persist reliably, even on dynamic websites like YouTube, thanks to a
MutationObserver-based re-application system. -
SPA Compatibility: Advanced support for Single Page Applications (SPAs) with intelligent URL change detection and annotation management.
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Smart URL Handling: Intelligent parameter filtering for consistent annotation storage across different URL variations.
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Robust Anchoring: Every annotation stores the exact quote, a few words of context and its position (W3C-style selectors). When a page changes, highlights are re-anchored with fuzzy matching and heal themselves in the background.
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Orphaned Annotations Stay Visible: If a passage disappears from a page, the annotation is kept in the sidebar (marked as orphaned) and re-anchored automatically on later visits.
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Copy to Clipboard: One click in the annotation menu copies the highlighted text.
- Full-Featured Editor: Powered by Tiptap, the comment editor supports rich formatting.
- Formatting Toolbar: Includes tools for bold, italic, underline,
strikethrough, links, code blocks, quotes, and headings (H1, H2, H3). - Smart Link Tool: Create and edit links with a custom modal. Hover over links to see their URL, and
Ctrl+Clickto open them in a new tab. - Dynamic Placeholders: Context-aware help text guides you as you write.
- Centralized Management: A dedicated panel to view and manage all your annotations for the current page.
- Page Metadata: The sidebar displays the page's title, description, domain, and favicon for context.
- Click-to-Scroll: Instantly navigate to any annotation on the page by clicking its card in the sidebar.
- Resizable & Lockable: Drag the edge to resize the sidebar and lock its width to your preference.
- Everything in One Place: A full-page panel lists every annotation from every website, grouped by page with its title and favicon, without opening any of those pages.
- Search & Filters: Full-text search across quotes and comments, plus filters by color, type, site and date, and several sort orders.
- Edit from the Panel: Change colors, switch between highlight and underline, edit rich-text comments, add page notes and delete annotations directly.
- Jump Back to the Source: Open the original page scrolled to the highlighted passage.
- Export: Download the visible annotations as Markdown or JSON, or copy a page's annotations as Markdown.
- Always Reachable: Open it from the sidebar, from the toolbar icon's right-click menu, or by clicking the icon on pages where the sidebar cannot load (for example Chrome's internal pages).
- Granular Control: Disable the extension on a specific page or an entire website.
- Force Dark Text: An option to force black text on highlights to ensure readability on any background.
- Force Solid Highlights: Replace translucent highlights with solid colors on pages where the blend is hard to read.
- Sidebar Dark Mode: A dark theme for the sidebar and the annotations panel, remembered across sessions.
- Automatic Synchronization: Out of the box, your annotations and settings are saved to your Google account via
chrome.storage.sync— no sign-in required. - Optional Google Drive Sync: Connect your Google account from the sidebar settings to sync annotations through a hidden, extension-private folder in your own Google Drive, removing the ~100 KB limit of Chrome's built-in sync. The extension only requests the
drive.appdatascope: it can never see the rest of your Drive files. Disconnecting keeps a full local copy on your device. - Seamless Experience: Access your notes on any device where you're signed in. If you make changes while offline, they are queued and uploaded automatically as soon as you reconnect.
- Privacy-Focused: Both mechanisms store data in your Google account, governed by Google's privacy policy. Your data is never sent to any developer-operated or third-party server.
- Multi-Language Support: The entire interface is professionally translated into 6 languages:
- English (en)
- Spanish (es)
- French (fr)
- Portuguese (Brazil) (pt_BR)
- Russian (ru)
- Chinese (Simplified) (zh_CN)
- Localized Placeholders: All help texts are culturally adapted.
- Smart Context Menus: Annotation menus are intelligently positioned using Floating UI to prevent them from going off-screen.
- Precise Selection: Automatically trims leading/trailing whitespace from selections to keep your notes clean.
- Intuitive Shortcuts: A comprehensive set of keyboard shortcuts for a faster workflow.
| Shortcut | Action | Context |
|---|---|---|
Ctrl+Shift+H |
Toggle the sidebar | Global |
Esc |
Close annotation menu or cancel selection | On-Page |
Delete |
Delete the selected annotation | On-Page |
Ctrl+Click |
Open link in a new tab | On a link in a comment |
Ctrl+B |
Toggle Bold | Comment Editor |
Ctrl+I |
Toggle Italic | Comment Editor |
Ctrl+U |
Toggle Underline | Comment Editor |
Ctrl+Shift+X |
Toggle |
Comment Editor |
Ctrl+K |
Add/Edit Link | Comment Editor |
Ctrl+Shift+7 |
Toggle Blockquote | Comment Editor |
Ctrl+Shift+8 |
Toggle Code Block | Comment Editor |
Ctrl+Alt+1 |
Toggle Heading 1 | Comment Editor |
Ctrl+Alt+2 |
Toggle Heading 2 | Comment Editor |
Ctrl+Alt+3 |
Toggle Heading 3 | Comment Editor |
Install the extension directly from the Chrome Web Store for the most stable version and automatic updates.
➡️ Install from Chrome Web Store
If you prefer to install manually or want to test the latest development version:
- Download: Download or clone this repository.
- Open Chrome: Navigate to
chrome://extensions/. - Enable Developer Mode: Turn on the "Developer mode" toggle in the top-right corner.
- Load the Extension: Click "Load unpacked" and select the
chrome_extensionfolder from this repository. - Done! The extension icon will appear in your toolbar.
- Select Text: Drag your mouse over any text on a webpage.
- Choose Type & Color: A floating menu will appear. First, select the annotation type (highlight or underline), then choose one of the 8 available colors.
- Annotation is Created: The annotation is instantly created and saved.
- Click an Annotation: Click on any existing highlight or underline on the page.
- Edit Menu: The context menu will appear, allowing you to change the color, type, or delete the annotation.
- Add a Comment: Use the integrated Tiptap editor to write and format your comments. Changes are saved automatically.
- Open Sidebar: Click the extension icon or use the
Ctrl+Shift+Hshortcut. - Navigate Annotations: See all annotations organized in a list.
- Scroll to, Edit, or Delete: Click any annotation card to scroll to its position on the page. Use the buttons on the card to edit or delete it.
- Adjust Width: Drag the left edge to resize the sidebar and use the lock icon to fix its size.
- Open the Panel: Click the grid icon in the sidebar header, or right-click the extension icon and choose View all my annotations.
- Find Anything: Search by text, or filter by color, type, site or date. Groups are collapsible per page.
- Edit in Place: Change the color or type, edit the comment with the rich-text editor, add page notes, or delete annotations. Open tabs showing that page refresh automatically.
- Export: Use the Export menu to download the visible annotations as Markdown or JSON.
Version numbers follow YYYY.MMDD.N (publication date plus a daily counter). The Chrome Web Store compares versions number by number and only accepts strictly increasing ones, which is why the month and day keep their leading zeros.
| Version | Date | Highlights |
|---|---|---|
| 2026.0905.2 | 2026-09-05 | Global All annotations panel (search, filters, editing, page notes, Markdown/JSON export), support links moved from PayPal to Stripe, new store marquee, legal documents aligned with the Chrome Web Store policies in force since August 2026. |
| 2026.0708.1 | 2026-07-08 | Optional Google Drive sync, robust W3C-style anchoring with self-healing, orphaned annotations surfaced instead of hidden, storage chunking measured in bytes, copy-to-clipboard button. |
| 2025.0816.1 | 2025-08-16 | Sidebar dark mode, force solid highlights, storage chunking, extension name in the sidebar header. |
| 2025.0802.1 | 2025-08-02 | Official launch on the Chrome Web Store. |
- Chrome Extension Manifest V3: Modern, secure, and performant extension architecture.
- Vanilla JavaScript (ES6+): No heavy frameworks for the core logic, ensuring a lightweight footprint.
- Tiptap: A headless, framework-agnostic rich-text editor for advanced comments.
- Floating UI: A powerful library for intelligently positioning floating elements like context menus.
- Custom i18n System: A dependency-free internationalization system.
- approx-string-match (vendored): Approximate string matching used to re-anchor highlights when a page changes.
The extension is designed with your privacy in mind. Your data lives in your browser's storage and — only if you opt in — in a hidden, extension-private folder of your own Google Drive; it is never sent to any server operated by the developer. The sidebar and the All annotations panel are pages of the extension that read that same storage. The extension ships no remote code and no analytics, and its documents are kept aligned with the Chrome Web Store Developer Program Policies (including the Limited Use and Disclosure Requirements updates enforced since August 1, 2026). What it stores and where is stated inside the product too: on the welcome page and in a short notice shown until you acknowledge it, which also lists any change in data practices after an update. For more details, please see the following documents:
- Privacy Policy: Understand how your data is handled.
- Permissions and Data Usage: A detailed explanation of the permissions requested by the extension.
- Store Listing Texts: The exact texts declared in the Chrome Web Store Developer Dashboard.
- Security Policy: Our commitment to keeping the extension secure.
Contributions are welcome! Please:
- Fork the repository.
- Create a feature branch (
git checkout -b feature/new-feature). - Commit your changes (
git commit -am 'Add some new feature'). - Push to the branch (
git push origin feature/new-feature). - Open a Pull Request.
- 🌍 Translations into new languages or improving existing ones.
- 🎨 UI/UX improvements.
- 🐛 Bug fixes.
- 📚 Documentation.
- ⚡ Performance optimizations and code refactoring.
Quantum Highlighter PRO is a free, open-source project developed with love in my spare time. If you find the extension useful, you can buy me a coffee: each one is 5 USD and you can pick how many at checkout. Payments are processed securely by Stripe.
This project is licensed under the Creative Commons Attribution-ShareAlike 4.0 International License. This means you are free to:
- Share: Copy and redistribute the material in any medium or format.
- Adapt: Remix, transform, and build upon the material for any purpose, even commercially.
Under the following terms:
- Attribution: You must give appropriate credit, provide a link to the license, and indicate if changes were made.
- ShareAlike: If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.
Developed with ❤️ by Jorge Antonio Gómez