PyTorrent – Simple BitTorrent Client with Web Dashboard

🎥 Video Demo

https://youtu.be/-bEryA4tv2g

---

📌 What is PyTorrent?

PyTorrent is a Python-based BitTorrent client with a web interface.
Instead of running everything in a terminal, you can upload a .torrent file in your browser, start the download, and watch what’s happening in real time.

This project was built as a CS50x Final Project and focuses on:

• Understanding how BitTorrent works internally
• Using asyncio for real network-heavy tasks
• Connecting a low-level backend with a clean web UI

---

🧠 How It Works (High-Level)

PyTorrent has two main parts:

1️⃣ BitTorrent Engine (Backend Logic)

This part:

• Reads .torrent files
• Talks to trackers to find peers
• Connects to multiple peers at the same time
• Downloads files piece by piece
• Verifies each piece using SHA-1 hashing

2️⃣ Web Dashboard (Frontend + Controller)

This part:

• Lets users upload .torrent files
• Starts the download process
• Shows live logs and progress
• Keeps the app responsive while downloads run in the background

---

📁 Project Structure (Simple Explanation)

project/
│
├── app.py
│   → Flask web server and main entry point
│
├── torrent_wrapper.py
│   → Runs the async BitTorrent engine safely in the background
│
├── torrent_client/
│   ├── parser.py
│   │   → Decodes .torrent files (bencoding)
│   ├── get_peers.py
│   │   → Contacts trackers and finds peers
│   ├── connect_to_peer_async.py
│   │   → Handles peer connections and downloads
│   └── __init__.py
│
├── downloads/
│   → Final downloaded files
│
├── requirements.txt
│
└── README.md

---

🔍 Key Features Explained Simply

✅ Real BitTorrent Protocol

This project follows the official BitTorrent specification (BEP 0003) instead of using libraries like libtorrent.

🔐 File Verification (SHA-1)

Each downloaded piece is verified using SHA-1 hashing.
If a piece is corrupted, it is discarded and downloaded again.

📡 Real-Time Updates (SSE)

The dashboard uses Server-Sent Events (SSE) to stream logs and progress updates live to the browser.

🧵 Async + Flask Bridge

Flask is synchronous, but BitTorrent is async. A background thread runs an asyncio event loop so downloads don’t freeze the web server.

---

⚙️ Installation & Setup

1️⃣ Create Virtual Environment

python3 -m venv venv
source venv/bin/activate   # Mac/Linux
venv\Scripts\activate    # Windows

2️⃣ Install Dependencies

pip install Flask werkzeug

---

▶️ Running the App

python3 app.py

Then open:

http://127.0.0.1:5000

---

🧪 How to Use

1. Open the dashboard in your browser
2. Upload a .torrent file
3. Click Start Download
4. Watch logs and progress update live
5. Downloaded file appears in the downloads/ folder

---

🙌 Final Words

PyTorrent helped me understand how real-world peer-to-peer systems work under the hood.
It combines networking, concurrency, cryptography, and web development into one complete system.