FocusWave is a productivity Chrome extension that blocks distracting websites using behavioral psychology and smart time-delayed unblocking. Unlike traditional website blockers, FocusWave implements a unique 12-minute waiting period before users can unblock sites—eliminating instant gratification and helping users stay focused. Built entirely using Replit’s AI-assisted development platform with Chrome Manifest V3, this case study reveals how to create a Chrome extension that solves real productivity problems.
Key Metrics:
- Development Platform: Replit (AI-assisted rapid prototyping)
- Technology: JavaScript, Chrome Extension Manifest V3, Luxon.js
- Extension Size: 50.51KB (optimized for performance)
- Privacy: 100% local storage, zero data collection
- Target Audience: Students, remote workers, professionals seeking focus
The Problem: Why Traditional Website Blockers Fail
Digital distractions cost productivity. Studies show the average person checks their phone 96 times per day, and 47% of workers admit social media distracts them at work. Traditional website blocking extensions have a critical flaw: users can disable them instantly when temptation strikes.
Common Website Blocker Problems:
- Instant unblocking defeats the purpose
- No behavioral reinforcement
- Users bypass blockers during weak moments
- Lack of scheduled blocking for work hours
- Poor user experience with generic error pages
Target Users Searching For:
- “How to block websites on Chrome”
- “Best productivity extension for Chrome”
- “Website blocker that can’t be disabled”
- “Focus app for students”
- “Block social media during work hours”
The Solution: A Smart Website Blocker with Time-Delayed Unblocking
FocusWave is a Chrome extension that blocks websites using a psychology-backed approach: the 12-minute unblock delay. When users try to unblock a distracting website, they must wait 12 minutes—long enough for the urge to pass. This makes FocusWave the best Chrome extension for serious focus seekers.
Top Chrome Extension Features
1. Intelligent Website Blocking System
- Block entire domains (e.g., “twitter.com” blocks all Twitter pages)
- Block specific URL paths for granular control
- Uses Chrome’s declarativeNetRequest API for efficient blocking
- No performance impact on browser speed
2. Flexible Scheduling for Maximum Productivity
- Time-based website blocking: Set schedules (weekdays 9AM-5PM)
- Permanent website blocks: Complete blocking until changed
- Per-site configurations: Different rules for different distractions
- Perfect for work-from-home schedules and study sessions
3. The Game-Changing 12-Minute Wait Period
- Unblocking triggers a countdown timer (behavioral psychology)
- Instant blocking when you need focus (no delays)
- Cancel timers by re-blocking immediately
- Timers persist even if browser closes (using chrome.alarms)
- Forces “urge surfing” – wait out the temptation
4. Motivational Block Page (Better Than Generic Errors)
- Custom redirect page instead of “Page Not Found”
- Random inspirational quotes about focus and productivity (20+ quotes)
- Visual log of blocked attempts with timestamps
- Builds self-awareness of distraction patterns
- SEO-friendly for “productivity quotes” searches
5. User-Friendly Chrome Extension Interface
- Clean options page accessed via extension icon
- Real-time countdown display for active timers
- Guided setup for first-time users
- Tooltip shows active unblock timers
- Intuitive design for non-technical users
How to Build a Chrome Extension: Technical Architecture
Replit AI-Assisted Development Workflow
FocusWave was built using Replit, an online IDE with AI-assisted coding capabilities. This development approach offers significant advantages for indie developers and startups:
Benefits of Building Chrome Extensions in Replit:
- Rapid prototyping with AI-generated code
- No local development environment setup required
- Instant testing and iteration
- Built-in version control
- Easy collaboration and code sharing
- Fast path from idea to Chrome Web Store
Development Process:
- Created detailed prompt with all extension requirements
- Used Replit AI to generate Manifest V3 boilerplate
- Iteratively refined features and UI
- Tested locally with Chrome’s “Load unpacked” feature
- Published to Chrome Web Store
Chrome Extension Technology Stack
Chrome Manifest V3 (Latest Standard)
✓ Service Worker architecture (background.js)
✓ DeclarativeNetRequest API for blocking rules
✓ Chrome Storage Sync for cross-device settings
✓ Alarms API for persistent timers
✓ Notifications API for unblock alerts
Best Practices for Chrome Extensions:
- Manifest V3 compliance (required for Chrome Web Store)
- Minimal permissions (builds user trust)
- Vanilla JavaScript (no framework bloat)
- Local storage only (privacy-first approach)
- Lightweight bundle (<100KB recommended)
Libraries Used:
- Luxon.js: Industry-standard date/time handling for schedules
- No React/Vue/Angular: Pure JavaScript for maximum performance
Chrome Extension File Structure:
manifest.json → Extension configuration, permissions
background.js → Service worker (replaces deprecated background pages)
options.html → User interface for settings
options.js → Configuration logic
block.html → Custom block/redirect page
block.js → Quote randomization, blocked attempt logs
luxon.min.js → Time zone and schedule handling
icons/ → Extension icons (16px, 48px, 128px)