yt2ai/README.md

YT2AI - YouTube Subtitle Extraction & AI Summarization Bookmarklet

One-click YouTube subtitle extraction for AI-powered educational content analysis on Android Chrome

Overview

YT2AI is a lightweight, mobile-optimized bookmarklet that extracts YouTube auto-generated subtitles and prepares them for AI analysis. Designed specifically for Android Chrome users who want to quickly evaluate educational YouTube content without watching entire videos.

Key Benefits

• ⚡ 2-3 minute evaluation instead of 10-20 minutes of uncertain viewing
• 📱 Mobile-first design optimized for Android Chrome
• 🧠 AI-ready output formatted for Claude.ai integration
• 🚫 Zero installation required - works as a simple bookmark
• 🔒 Privacy-focused - no data storage or tracking
• 🎯 85% technical success rate for subtitle extraction

Quick Start

Installation (30 seconds)

1. Copy the bookmarklet code:

   javascript:(function(){/* Minified code here - get from releases */})();
   

2. Create bookmark in Chrome:

   • Open Chrome on Android
   • Tap the ⭐ (bookmark) icon in address bar
   • Edit the bookmark
   • Replace URL with the copied javascript code
   • Name it "YT2AI Extractor"
   • Save

3. Use on any YouTube video:

   • Navigate to a YouTube video page
   • Tap your "YT2AI Extractor" bookmark
   • Wait for extraction (5-30 seconds)
   • Content is copied to clipboard and Claude.ai opens

Usage Workflow

YouTube Video → Tap Bookmarklet → Subtitle Extraction → Claude.ai Analysis
    (1s)            (5-30s)              (Auto)

Features

🎯 Core Functionality

• Automatic video detection from YouTube URLs (watch, shorts, embed)
• Subtitle extraction via downloadyoutubesubtitles.com API
• Claude.ai integration with automatic tab opening
• Clipboard fallback for manual paste scenarios
• CAPTCHA handling with user guidance

📱 Mobile Optimization

• 44px touch targets for WCAG AA compliance
• Portrait-optimized UI with mobile breakpoints
• Touch gesture support (touchend events)
• Network-aware timeouts for mobile connections
• Memory-efficient (<10MB usage)

🛠️ Developer Experience

• Comprehensive debugging in development mode
• Performance monitoring with memory tracking
• Error reporting with stack trace capture
• Mobile environment detection
• Zero build dependencies in production

Technical Specifications

Browser Requirements

• Android Chrome 90+ (primary target)
• Mobile viewport optimized experience
• JavaScript ES6+ feature support
• Clipboard API for copy functionality

Architecture

• Vanilla JavaScript - no external dependencies
• Single-file distribution - 8.7KB minified
• Mobile-first responsive design
• CSP-compliant code structure
• YouTube-safe CSS (yt2ai- prefixed)

Performance Targets

• Initialization: <100ms
• Subtitle extraction: <60s normal conditions
• Memory usage: <10MB peak
• Bundle size: <10KB compressed

Installation Guide

For End Users

Method 1: Direct Installation (Recommended)

1. Get the latest bookmarklet:

   • Visit the Releases page
   • Copy the code from bookmarklet.min.js

2. Install in Chrome Mobile:

   • Open Chrome on your Android device
   • Go to any webpage
   • Tap the star (⭐) icon in the address bar
   • Tap "Edit" on the bookmark
   • Replace the URL field with the copied javascript code
   • Change the name to "YT2AI Extractor"
   • Tap "Save"

3. Test the installation:

   • Go to any YouTube video
   • Tap your new bookmark
   • You should see a "YT2AI Ready!" message

Method 2: QR Code Installation

1. Scan the QR code below to open the installation page
2. Follow the mobile-optimized installation wizard
3. The bookmarklet will be automatically configured

For Developers

Development Setup

# Clone repository
git clone https://github.com/yt2ai/yt2ai-bookmarklet.git
cd yt2ai-bookmarklet

# Install dependencies
npm install

# Run development build
npm run build:dev

# Run tests
npm test

# Start development with file watching
npm run build:watch

Build Commands

npm run build          # Production build
npm run build:dev      # Development build with debugging
npm run test           # Run unit tests
npm run lint           # Code linting
npm run format         # Code formatting
npm run verify         # Full verification pipeline

Usage Instructions

Basic Usage

1. Navigate to YouTube video - Any video with auto-generated subtitles
2. Tap bookmarklet - Use your saved "YT2AI Extractor" bookmark
3. Wait for processing - Usually 5-30 seconds depending on video length
4. Get results - Claude.ai opens with formatted subtitle content

Supported Video Types

• ✅ Standard YouTube videos (youtube.com/watch?v=)
• ✅ YouTube Shorts (youtube.com/shorts/)
• ✅ Embedded videos (youtube.com/embed/)
• ❌ Playlists (navigate to specific video first)
• ❌ Live streams (subtitles not available)

What Gets Extracted

• Auto-generated English subtitles (when available)
• Video metadata (title, duration, video ID)
• Formatted for AI analysis with structured prompts
• Mobile-optimized output for easy reading

Troubleshooting

Common Issues

"No subtitles found"

• Cause: Video doesn't have auto-generated English subtitles
• Solution: Try a different video or check if subtitles exist manually

"CAPTCHA required"

• Cause: Subtitle API requires verification
• Solution: Follow the mobile-friendly CAPTCHA guidance popup

"Please navigate to a video"

• Cause: Not on a valid YouTube video page
• Solution: Make sure you're on youtube.com/watch?v=... or similar

Bookmarklet doesn't work

• Check installation: Ensure javascript: prefix is included
• Check browser: Must be Chrome 90+ on Android
• Check network: Ensure internet connection is stable

Debug Mode

Add ?debug=true to any YouTube URL to enable detailed logging:

https://www.youtube.com/watch?v=VIDEO_ID&debug=true

Mobile Considerations

Android Chrome Optimization

• Touch-first interactions with 44px minimum targets
• Portrait orientation optimized layouts
• Mobile network timeouts (30s vs 15s desktop)
• Memory management for resource-constrained devices
• Gesture-friendly UI with swipe and tap support

Network Handling

• Adaptive timeouts based on connection quality
• Retry logic for mobile network instability
• Progress indicators for longer operations
• Offline graceful degradation

Battery Optimization

• Minimal CPU usage with efficient JavaScript
• Quick execution to minimize active processing time
• Automatic cleanup to free memory resources
• No background processes or persistent connections

Security & Privacy

Privacy Principles

• No data collection - bookmarklet is stateless
• No user tracking - no analytics or telemetry
• Local processing only - no data sent to YT2AI servers
• YouTube data only - accesses only public subtitle data

Security Features

• Input validation for all user data
• XSS protection through proper escaping
• CSP compliance with YouTube's security policies
• No external dependencies in production builds

Third-Party Services

• downloadyoutubesubtitles.com - For subtitle extraction only
• Claude.ai - User's own subscription for AI analysis
• No tracking services - Google Analytics, Facebook Pixel, etc.

Development

Architecture Overview

src/
├── core/                    # Future: Core extraction logic
├── ui/                      # Future: UI components
├── utils/                   # Future: Utility functions
└── bookmarklet.js          # Main entry point (current)

build/
├── webpack.config.js       # Build configuration
└── README.md              # Build system documentation

tests/
├── unit/                  # Unit tests
├── integration/           # Integration tests
└── manual/               # Manual testing protocols

Contributing Guidelines

1. Fork the repository and create a feature branch
2. Follow coding standards - ESLint and Prettier configurations
3. Add tests for new functionality (80% coverage target)
4. Test on real devices - Android Chrome compatibility
5. Update documentation for user-facing changes

Code Standards

• Vanilla JavaScript ES6+ - no frameworks or libraries
• Mobile-first development - touch and gesture optimized
• Comprehensive error handling - all async operations wrapped
• Performance monitoring - development mode metrics
• Accessibility compliance - WCAG AA standards

API Integration

Subtitle Extraction API

• Service: downloadyoutubesubtitles.com
• Method: GET requests with video ID
• Format: JSON response with subtitle text
• Rate limiting: Client-side throttling implemented
• Error handling: Comprehensive retry logic

Claude.ai Integration

• Method: Browser tab automation
• Fallback: Clipboard copy for manual paste
• Format: Structured prompts for consistent analysis
• Privacy: Uses user's existing Claude.ai subscription

Browser Compatibility

Supported Browsers

• ✅ Chrome 90+ (Android) - Primary target, fully tested
• ✅ Chrome 90+ (Desktop) - Secondary support for development
• ❌ Firefox Mobile - Not supported (different bookmarklet handling)
• ❌ Safari Mobile - Not supported (iOS restrictions)
• ❌ Samsung Internet - Not tested

Feature Detection

• Clipboard API - Graceful fallback to document.execCommand
• Performance API - Development-only, safe degradation
• Network Information - Progressive enhancement only
• Touch Events - Mobile-optimized with click fallbacks

Performance

Bundle Analysis

• Production size: 8.7KB minified
• Development size: 13.6KB with debugging
• Compression ratio: 36% size reduction
• Load time: <100ms on mobile networks

Runtime Performance

• Initialization: <100ms target
• Memory usage: <10MB peak, <5MB typical
• CPU usage: Minimal, <1% during extraction
• Network requests: 1-2 per extraction cycle

Mobile Optimization

• Code splitting: Single file for bookmarklet constraints
• Tree shaking: Unused code eliminated in production
• Minification: Terser with mobile-optimized settings
• Polyfills: Only for required ES6+ features

Roadmap

Version 1.1 (Next Release)

• RPA automation for Claude.ai form filling
• Enhanced error recovery with automatic retries
• Performance optimizations for slower devices
• Extended browser support testing

Version 1.2 (Future)

• Multiple AI providers support (GPT, Gemini)
• Subtitle language options beyond English
• Batch processing for playlist support
• Custom prompt templates for different use cases

Long-term Vision

• Progressive Web App version for enhanced mobile experience
• Browser extension for advanced features
• API service for developers and integrations
• Analytics dashboard for usage insights (opt-in)

Support

Getting Help

• GitHub Issues - Bug reports and feature requests
• Discussions - Community support and questions
• Wiki - Extended documentation and guides
• Email Support - For private or urgent issues

Community Resources

• Developer Guide - Extended technical documentation
• Mobile Testing Guide - Device-specific testing procedures
• Integration Examples - Sample implementations
• Video Tutorials - Step-by-step usage guides

License

MIT License - see LICENSE file for details.

Acknowledgments

• downloadyoutubesubtitles.com - Reliable subtitle extraction API
• Claude.ai - AI analysis capabilities
• Android Chrome team - Excellent mobile browser platform
• Open source community - Testing and feedback

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Made with ❤️ for mobile educational content consumption

For more information, visit our documentation site or check the developer guide.