You can build a fully local, cloud-free home alarm system using Z-Wave door and window sensors, motion detectors, and a siren connected to Home Assistant
via a Z-Wave JS controller. The built-in alarm_control_panel integration combined with automations handles arming, disarming, entry delays, and siren activation entirely on your local network. No cloud subscription, no monthly monitoring fee, and the alarm keeps working even when your internet goes down.
Professional monitored systems like SimpliSafe and Ring Alarm cost $10-25 per month and route every sensor event through a company’s cloud servers. If their servers go down or the company decides to change pricing, your security system is at their mercy. A local Z-Wave setup running on Home Assistant puts you in full control. The total hardware cost is roughly $250-350 for a three-bedroom home, with zero ongoing fees. The trade-off is that you handle configuration, testing, and monitoring yourself - but if you are already running Home Assistant, you have the skills to make this work.