Countdown Timer - Browser Extension

Countdown Timer is a cross-browser extension for tracking important events with clean, visual countdown timers right on your New Tab page. Built with the WXT framework and TypeScript, supporting Chrome, Firefox, and Edge.

Links

• Public repository: https://github.com/mjfutera/CountdownTimer-Browser-extension
• Project page: https://michalfutera.pro/my-projects/countdown-timer-chrome-extension/
• Author website: https://michalfutera.pro
• Telegram: https://t.me/MichalFuteraPro

Socials

           

Key Features

• Multiple countdown timers in one place
• New Tab integration for quick access
• Progress indicators and clean timer cards
• Browser notifications for timer milestones
• Persistent storage and schema migration support
• Cross-browser support (Chrome, Firefox, Edge)

Stack and Structure

• WXT framework with TypeScript
• Manifest V3
• Vite bundler
• utils/core.ts for date/time logic
• utils/storage.ts for persistence and migrations
• utils/ui.ts for rendering helpers
• utils/notifications.ts for sound/notifications
• entrypoints/background.ts for alarms lifecycle
• entrypoints/newtab/ for the New Tab page

Quality

• Prettier
• Automated publishing via wxt submit

---

How to run the extension from source code (Opera/Chromium)

1. Download the source code from GitHub (Code → Download ZIP or git clone ...).
2. Install Node.js (https://nodejs.org/) if you don't have it already.
3. Open a terminal in the project folder and run:

   npm install
   npm run build
   

4. Go to the .output/chrome-mv3 folder.
5. In Opera (or Chrome/Edge):
   • Open: Extensions → Manage extensions (opera://extensions)
   • Enable developer mode.
   • Click Load unpacked and select the .output/chrome-mv3 folder.

The extension will appear in your browser and work without being published in the store.