Silent Duo Chat

Anonymous, registration-free web chat for exactly two participants.

Built for quick private conversations with ephemeral rooms, one-time invite links, and automatic data cleanup.

Features

• One-click room creation
• One-time invite link for the second participant
• Strict 2-user room limit
• Real-time messaging with Socket.IO
• File and image sharing
• Paste image from clipboard
• Reply-to-message support
• Full-size image preview modal
• Typing indicator
• Automatic room termination when one participant leaves
• Automatic cleanup of chat history and uploaded files

How It Works

1. User A creates a room.
2. The server returns:
   • hostUrl for User A
   • inviteUrl for User B
3. User B joins using the one-time invite.
4. The room becomes active for two users only.
5. If either user leaves/disconnects, the room is destroyed.
6. Messages and temporary uploads are removed from memory/disk.

Tech Stack

• Backend: Node.js, Express, Socket.IO, Multer
• Frontend: Vanilla HTML/CSS/JS
• Public Access: Cloudflare Tunnel (trycloudflare.com)

Project Structure

.
├─ public/              # Frontend (landing + chat UI)
├─ scripts/             # Utility scripts (e.g. free-port)
├─ tests/               # Smoke tests
├─ uploads/             # Temporary uploaded files (auto-cleaned)
├─ room-manager.js      # Room lifecycle + state machine logic
├─ server.js            # HTTP + socket transport layer
├─ package.json
└─ README.md

Room State Machine

Room lifecycle is strictly controlled server-side:

CREATED -> WAITING_SECOND -> ACTIVE -> DESTROYED

The server is the only authority for:

• joining
• leaving
• destroying
• TTL expiration

Getting Started

1) Install dependencies

npm install

2) Run locally

npm start

Open: http://localhost:3000

3) If port 3000 is already in use

npm run start:clean

Public Access (Internet)

Start with Cloudflare Tunnel:

npm run start:public

The console will print:

Public tunnel URL: https://...trycloudflare.com

Use that URL to access/share the app.

If port 3000 is busy:

npm run start:public:clean

Available Scripts

• npm start - Start server on local network.
• npm run dev - Same as start (simple dev mode).
• npm run start:clean - Free port 3000 and start server.
• npm run start:public - Start server with Cloudflare public tunnel.
• npm run start:public:clean - Free port 3000 and start public mode.
• npm run test:smoke - Run basic end-to-end smoke checks.

Security & Privacy

Implemented protections include:

• Anti-cache headers (no-store, no-cache, Expires: 0)
• Security headers (CSP, X-Frame-Options, nosniff, etc.)
• Ephemeral in-memory message history
• Automatic room TTL cleanup
• Temporary file deletion on room destruction
• URL token removal from browser address bar after join

Note: No web app can fully erase a user's browser history/downloads on their device.

Testing

Run smoke tests:

npm run test:smoke

Checks include:

• two participants can join
• third participant is blocked
• room is destroyed on leave

Troubleshooting

MODULE_NOT_FOUND (e.g. express)

You are likely in the wrong folder or dependencies are missing.

npm install

Public URL does not work (NXDOMAIN)

trycloudflare URLs are temporary. Restart public mode and use the new URL printed in console.

File upload returns server error

Ensure you are running the latest code and dependencies:

npm install
npm run start:public

License

ISC