PhantomChat

PhantomChat is a portable, completely offline, and anonymous messaging system built for ESP32 microcontrollers. It requires no internet, no cellular service, and no external infrastructure.

By utilizing the ESP32 as a standalone Wi-Fi Access Point and a DNS-driven Captive Portal, PhantomChat creates an instant local chat room. Anyone who connects to the device's Wi-Fi network is automatically greeted with a modern, responsive web app directly on their screen
NO APP INSTALLATION REQUIRED.

Real-World Applications

PhantomChat is designed for situations where traditional networks are unavailable, untrusted, or overloaded:

• Off-Grid & Camping: Communicate with your group around a large campsite or at a festival where cell towers are overloaded or nonexistent.
• Airplanes & Cruises: Devices can connect to the local ESP32 network while maintaining airplane mode, allowing families or colleagues to chat across the cabin without purchasing expensive satellite Wi-Fi.
• Classrooms & Offices: Pass messages silently in closed-room environments.
• Conventions & Crowded Events: Bypass congested cellular networks by maintaining a localized, private mesh for your team.
• Disaster Recovery: Instant pop-up communication in areas where infrastructure has been damaged by severe weather or power outages.

Key Features

• True Captive Portal: Works seamlessly on iOS, Android, macOS, and Windows. Connecting to the network automatically opens the chat interface.
• Modern Interface: A highly polished, mobile-first design featuring message bubbles, auto-scrolling, and clean typography.
• Anonymous & Color-Coded: Users are assigned a unique, random ID upon connection. Bubbles are automatically color-coded using a hashing algorithm based on the user's ID to easily distinguish participants.
• Custom Nicknames: Users can choose to remain completely anonymous or set a custom display name.
• Direct Messaging: Includes a dynamic dropdown menu to send private messages. (Note: Handled client-side for rapid local deployment).
• Interactive Reactions: Tap any message to open a floating menu and react to specific messages in real-time.
• Audio & Haptic Feedback: Built-in toggle for notification sounds and device vibration when new messages arrive (utilizing the Web Audio API to bypass strict browser media policies).
• Hardware LED Feedback: Integrates with onboard WS2812B RGB LEDs to blink visually when users join or messages are routed.

Advantages

• Absolute Privacy: There is no database, no central server, and no cloud storage.
• Zero Data Retention: The system operates entirely in the ESP32's volatile RAM. Once the power is disconnected, all messages, user IDs, and metadata are permanently destroyed.
• No Infrastructure Needed: It operates completely off-grid. If you have a battery pack and the ESP32, you have a functioning communication network.
• Cross-Platform Compatibility: Because the interface relies on standard HTML, CSS, and JavaScript, it works on any device with a web browser.

Hardware Compatibility

The firmware is lightweight and designed to run on the ESP32 architecture.

• Tested Boards: ESP32-WROOM, ESP32-C3 Zero, ESP32-S2, ESP32-S3.
• LED Support: Built-in support for WS2812B LEDs. (Configured to Pin 10 by default for ESP32-C3 Zero boards, easily adjustable in the code).
• Power Requirements: Can be run from a standard USB power bank or integrated with a 3.7V LiPo battery and a TP4056 charging module for a pocket-sized form factor.

Flashing Instructions

To deploy PhantomChat to your ESP32, follow these steps using the Arduino IDE:

1. Prerequisites

• Install the latest Arduino IDE.
• Install the ESP32 Board Manager (by Espressif Systems).
• Open the Library Manager (Sketch > Include Library > Manage Libraries) and install the Adafruit NeoPixel library.

2. Board Configuration

• Select your specific ESP32 board from the Tools menu.
• Crucial Step: To prevent Wi-Fi caching issues, ensure that "Erase All Flash Before Sketch Upload" is set to ENABLED in the Tools menu for the initial flash.

3. Uploading

1. Open the provided .ino file in the Arduino IDE.
2. If using a board other than the ESP32-C3 Zero, check the #define LED_PIN variable and adjust it to match your board's built-in RGB LED pin.
3. Connect your ESP32 via USB and select the appropriate COM port.
4. Click Upload.

4. Post-Install Network Reset

If you are flashing over an older version of PhantomChat, ensure you tell your smartphone or computer to "Forget" the Wi-Fi network before reconnecting to clear the device's Captive Portal cache.

Usage

1. Power the ESP32 via USB or battery.
2. Open the Wi-Fi settings on your phone, tablet, or laptop.
3. Connect to the network named PhantomChat.
4. The device should automatically prompt you to "Sign into network", which will open the chat interface. If it does not pop up automatically, open a web browser and navigate to 192.168.4.1.
5. Tap the Sound button to enable audio notifications, set a nickname, and begin chatting.

Disclaimer

This is a local, ad-hoc communication tool. Direct messages are filtered client-side for speed and simplicity. It is not intended for the transmission of highly sensitive or classified data against persistent, local network sniffers. Use responsibly.

License

Apache 2.0