AlarmCast is a low-cost smart safety system that adds remote notification capabilities to existing smoke and carbon monoxide (CO) detectors. Instead of requiring users to replace their current alarms with expensive smart devices, AlarmCast uses a small listener device built on a Raspberry Pi and microphone that monitors the sound patterns emitted by standard alarms. When the system detects a valid alarm signal, it sends an alert to users through SMS notifications and a companion mobile application. The system consists of three main components: a hardware listener device, a backend server, and a mobile application interface. The listener device continuously analyzes audio using a machine learning pipeline that classifies it using a convolutional neural network trained to distinguish fire alarms from other household sounds. When a valid alarm pattern is detected, the device communicates with a backend server that distributes alerts to designated users. AlarmCast is designed to improve safety accessibility by providing smart-home monitoring functionality without requiring proprietary hardware or complex installation. By working with existing alarms, the system provides a practical and affordable solution for renters, multi-unit households, and individuals who may not always be present to hear an alarm.