Just Between Us - Shhh...it's just between us.

Create a private chat room, share the link, and chat. The room disappears after 10 minutes (or you can destroy it manually). All messages are encrypted client-side using AES-256-GCM - the server never sees your encryption keys or plaintext messages.

Features

• Private rooms - Create a room, share the link, and start chatting without an account.
• End-to-end encrypted messages - Messages are encrypted in the browser with AES-256-GCM before they leave your device.
• Keys stay out of the server - Room keys are shared through the URL fragment, so they are never sent in API requests.
• No accounts or tracking - Just Between Us does not ask for signups or collect personal profile data.
• Real-time chat - Messages show up as they are sent, without refreshing the page.
• Fast by default - Built with Elysia (Bun-first framwork), Turbopack, and React Compiler for a snappy development and runtime experience.
• Short-lived by design - Rooms expire after 10 minutes, and you can destroy a room manually when you are done.
• Minimal PWA - A small, responsive interface that can be installed and still has a basic offline fallback.

📊 Project Flow Diagram

Diagram: Just Between Us app architecture, encryption, and real-time flow.

🔗 View Interactive Flow Diagram on tldraw

🛠️ Tech Stack

Frontend

• Next.js 16 - React framework with App Router
• React 19 - Latest React with React Compiler
• Tailwind CSS v4 - Modern utility-first CSS framework
• TanStack Query - Powerful data synchronization for React

Backend & Infrastructure

• Elysia - Fast, type-safe web framework (Bun runtime)
• Upstash Redis - Serverless Redis for data persistence
• Upstash Realtime - Real-time messaging infrastructure
• Zod - TypeScript-first schema validation

Development Tools

• TypeScript 5.0 - Type-safe development
• Turbopack - Next-generation bundler for fast development
• ESLint - Code linting and quality
• React Compiler - Automatic React optimization
• Bun - Fast JavaScript runtime and package manager
• Serwist - Service worker library for PWA functionality and offline support

🚀 Getting Started

Prerequisites

• Node.js 18+ or Bun (recommended)
• Upstash Redis account (free tier available)

Installation

1. Clone the repository

   git clone <repository-url>
   cd justbetweenus

2. Install dependencies

   bun install
   # or
   npm install

3. Set up environment variables

   Create a .env.local file in the root directory:

   UPSTASH_REDIS_REST_URL=your_redis_url
   UPSTASH_REDIS_REST_TOKEN=your_redis_token

4. Run the development server

   bun dev
   # or
   npm run dev

5. Open your browser

   Navigate to http://localhost:3000

🔑 How End-to-End Encryption Works

Just Between Us uses true end-to-end encryption to ensure your messages remain private. All encryption happens client-side using the browser's Web Crypto API - no external dependencies required.

Key Features

• AES-256-GCM Encryption - Industry-standard authenticated encryption
• Zero-Knowledge Architecture - Server never sees encryption keys or plaintext messages
• Secure Key Exchange - Keys shared via URL fragments (never transmitted to server)
• Unique IV per Message - Each message uses a random initialization vector for forward secrecy
• Client-Side Only - All encryption/decryption happens in your browser

For a detailed explanation of the encryption flow, key generation, message encryption, and security guarantees, see the End-to-End Encryption Documentation.

📄 License

This project is open source and available under the MIT License.

🤝 Contributing

Contributions, issues, and feature requests are welcome! Feel free to check the issues page.

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Built with ❤️ using Next.js, React, and modern web technologies