GaggiMate is an open-source smart espresso machine upgrade system that transforms a Gaggia Classic into an intelligent brewing platform with advanced control and monitoring capabilities. Built on ESP32 microcontroller hardware, it combines embedded C++ firmware (using Arduino/PlatformIO) with a modern Preact-based web interface to provide real-time temperature and pressure monitoring, multi-phase brew profiles with precise pressure/flow control, Bluetooth scale integration (Acaia, Hario, etc.), integrated grinder control, shot history analytics with visualized pressure curves, and WiFi-enabled remote access. The system features a modular plugin architecture supporting integrations with Home Assistant (MQTT), Apple HomeKit, automatic water level management, RGB LED feedback, and scheduled wake-up, all controlled through an LVGL-powered touchscreen display or web interface with over-the-air firmware update capabilities.