Udemy Transcript Downloader

A browser extension that enables you to download complete course transcripts from Udemy lectures as markdown files, organized by chapters and packaged into a convenient ZIP archive.

🎯 Features

• One-Click Download: Start downloading all transcripts from a course with a single click
• Chapter Organization: Transcripts are automatically organized into folders by chapter
• Pause & Resume: Pause downloads mid-process and resume exactly where you left off
• ZIP Export: All transcripts are bundled into a single ZIP file for easy distribution
• Merged Transcript: Includes a full course transcript combining all lectures
• Real-Time Progress: Live progress tracking shows exactly which lecture is being processed
• Robust Error Handling: Gracefully handles missing transcripts and API errors
• Cross-Browser Support: Works on Chrome/Edge and Firefox
• Lightweight & Efficient: Random request delays prevent API rate limiting

📋 How It Works

1. Navigate to any Udemy course lecture page (requires you to be enrolled)
2. Click the extension icon in your toolbar to open the popup interface
3. Click "Start Download" to begin fetching transcripts
4. The extension:
   • Extracts the course structure from the page
   • Fetches captions from Udemy's API for each lecture
   • Converts VTT format captions to readable markdown
   • Organizes lectures by chapter
   • Generates a ZIP file with individual chapter folders plus a merged full transcript
5. The ZIP file automatically downloads to your default download folder

Data Flow

Lecture Page (Data Extraction)
    ↓
Curriculum Fetch (Course Structure)
    ↓
Transcript Loop (Per Lecture)
    ├─ Caption Fetch (from Udemy API)
    ├─ VTT → Markdown Conversion
    ├─ Progress Update
    └─ Local State Persistence
    ↓
ZIP Generation (File Organization)
    ├─ Chapter Folders
    ├─ Individual .md Files
    └─ Full Transcript Merge
    ↓
Download Trigger

📥 Installation

Important

Chrome/Edge and Firefox: Not yet available on official extension stores. Use the manual installation steps below.

Click for manual installation instructions

Download from GitHub Releases

For Google Chrome/Edge:

1. Download the latest Chrome extension package from GitHub Releases
2. Extract the downloaded ZIP file to a folder on your computer.
3. Open Chrome/Edge and navigate to chrome://extensions/.
4. Enable Developer mode (toggle in the top right).
5. Click on Load unpacked.
6. Select the extracted folder containing the extension files.

For Mozilla Firefox:

1. Download the latest Firefox extension package from GitHub Releases
2. Extract the downloaded ZIP file to a folder on your computer.
3. Open Firefox and navigate to about:debugging#/runtime/this-firefox.
4. Click on Load Temporary Add-on....
5. Select the manifest.json file located inside the extracted folder.

The extension icon should now appear in your browser's toolbar.

🛠️ Development

Click to see setup instructions and development guide

Prerequisites

• Bun - JavaScript runtime and package manager
• Node.js 22+ (if not using Bun)
• Git

Setup

1. Clone the repository

   git clone <repository-url>
   cd udemy-transcript-downloader

2. Install dependencies

   bun install

3. Start development server

   bun run dev

   For Firefox:

   bun run dev:firefox

Project Structure

src/
├── entrypoints/
│   ├── content.ts              # Main content script - orchestrates downloads
│   └── popup/
│       ├── index.html          # Popup UI
│       ├── main.ts             # Popup controller and state binding
│       └── style.css           # Popup styling
├── utils/
│   ├── types.ts                # TypeScript interfaces
│   ├── udemy-api.ts            # Udemy API integration
│   ├── file-generator.ts       # ZIP file creation and download
│   ├── storage.ts              # Persistent state management
│   └── helpers.ts              # Utility functions
└── assets/                     # Extension assets (icons, etc.)

Available Commands

Command	Purpose
bun run dev	Start development with live reloading (Chrome/Edge)
bun run dev:firefox	Start development for Firefox with MV3
bun run build	Build extension for production (Chrome/Edge)
bun run build:firefox	Build extension for Firefox
bun run zip	Create distributable ZIP (Chrome/Edge)
bun run zip:firefox	Create distributable ZIP (Firefox)
bun run compile	Type-check TypeScript (no emit)

Type Checking

Always check for type errors when making changes:

bun run compile

Technology Stack

• Language: TypeScript 5.9+
• Framework: WXT 0.20.6+ (Web Extension Framework)
• Runtime & Package Manager: Bun 1.3.1+
• Compression: fflate 0.8.2 (ZIP compression)

📦 Architecture

Entry Points

Content Script (content.ts)

• Runs on Udemy course lecture pages (*://www.udemy.com/course/*/learn/lecture/*)
• Orchestrates the entire download workflow
• Implements pause/resume functionality through state management
• Recoverable: saves state after each lecture for crash resilience

Workflow:

1. Extract course ID and title from page DOM
2. Fetch complete course curriculum
3. Iterate through lectures and fetch transcripts
4. Save progress to persistent storage after each lecture
5. Generate ZIP file when complete
6. Support pause/resume mid-process

Popup Script (main.ts)

• Provides UI for user control (Start, Pause, Resume)
• Displays real-time progress, current task, and status badge
• Uses reactive storage watching for automatic UI updates
• Sends messages to content script to trigger actions

Popup UI (index.html + style.css)

• Clean, minimal interface matching Udemy's design language
• Progress bar with lecture counter
• Status badge (Idle, Running, Paused, Completed, Error)
• Current task description for transparency

API Endpoints:

• Curriculum: https://www.udemy.com/api-2.0/courses/{courseId}/subscriber-curriculum-items/
• Transcripts: https://www.udemy.com/api-2.0/users/me/subscribed-courses/{courseId}/lectures/{lectureId}/

Endpoints Used

1. Curriculum Endpoint

   GET /api-2.0/courses/{courseId}/subscriber-curriculum-items/
   

   Returns chapters, lectures, and quizzes with metadata

2. Lecture Endpoint

   GET /api-2.0/users/me/subscribed-courses/{courseId}/lectures/{lectureId}/
   

   Returns asset details including caption URLs

Error Handling

• Gracefully returns null for lectures without transcripts
• Continues processing even if individual lecture fails
• Logs errors for debugging without stopping the entire download

🔒 Permissions

The extension requests minimal permissions:

Permission	Purpose
storage	Persist download state locally
activeTab	Detect active Udemy page
host_permissions: https://www.udemy.com/*	API access to Udemy services

No data is sent to external servers except Udemy's official API.

💾 Auto Recover

Downloads are fully recoverable via persistent storage:

If the extension crashes or browser closes mid-download, users can click Resume to continue from the last completed lecture.

📝 File Output Format

ZIP Structure

CourseTitle_Transcripts.zip
├── 01_Chapter1/
│   ├── 01_Lecture1.md
│   ├── 02_Lecture2.md
│   └── ...
├── 02_Chapter2/
│   ├── 01_Lecture1.md
│   └── ...
└── CourseTitle_Full.md

Markdown Format

• Clean, plain text with light markdown formatting
• Timestamps and metadata removed for readability
• Properly formatted for note-taking and searching
• Compatible with all markdown viewers and note-taking apps

⚠️ Limitations

• Enrollment Required: Only works for courses you're enrolled in
• English Transcripts Only: Currently extracts English captions only
• Video Lectures Only: Skips non-video content (quizzes, documents)
• API Dependent: Requires Udemy API availability (can be shutdown by Udemy at any time)
• Rate Limiting: Random delays to prevent API throttling may increase download time

📄 License

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/

🤝 Contributing

Contributions are welcome! Feel free to:

1. Create a feature branch (git checkout -b feature/amazing-feature)
2. Make your changes and ensure type safety
3. Run type checking: bun run compile
4. Commit with conventional commit messages: feat:, fix:, docs:, etc.
5. Push and create a Pull Request

📚 Resources

• WXT Documentation - Web extension framework