Chat App

A real-time multi-room chat application built with a Python WebSocket backend and a vanilla JS frontend. No frameworks, no dependencies beyond the websockets library.

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Features

• Real-time messaging over WebSockets — no polling
• Multi-room support — join any named room, isolated from others
• Typing indicators with debounce so they don't spam
• Dark / light theme toggle, persisted in localStorage
• Connection status dot with live feedback and a reconnect button on drop
• Character counter (500 char limit enforced on both client and server)
• Rate limiting — max 5 messages per second per client, handled server-side
• Particle canvas on the welcome screen with mouse repulsion
• Browser history API — back/forward navigation works between screens

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Stack

Layer	Tech
Backend	Python 3, asyncio, websockets
Frontend	Vanilla JS, HTML, CSS (no frameworks)
Transport	WebSocket (ws://)

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Getting Started

Requirements: Python 3.10+

# Install the dependency
pip install websockets

# Start the server
python server.py

Then open index.html in your browser. That's it.

By default the server runs on ws://localhost:8765. To change it, edit WS_URL at the top of the <script> block in index.html, and HOST/PORT in server.py.

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Architecture

Browser (index.html)
    │
    │  WebSocket (ws://localhost:8765)
    ▼
server.py
    ├── rooms{}          # dict of room_name → set of (websocket, username)
    ├── client_activity  # per-client deque of timestamps for rate limiting
    └── broadcast()      # fans out a message to all clients in a room

Each client sends a join message on connect with a username and room name. After that, the server routes chat and typing messages to everyone else in the same room. Disconnects are caught in a finally block so the room always gets a leave notification.

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Project Structure

├── index.html    # entire frontend — UI, WebSocket logic, canvas animation
├── server.py     # async WebSocket server
└── favicon.svg

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License

MIT