Shelly BLU Door/Window

Quick verdict

A dirt-cheap Bluetooth contact sensor that does exactly what it should: report open/closed state with good battery life. The trade-off is that you need a Shelly BLU gateway or an ESPHome BLE proxy to get the data into Home Assistant. If you already have that gateway infrastructure, these sensors are an easy buy for covering every door and window in your home.

Standout: Ultra-cheap Bluetooth door/window sensor that works fully local through a Shelly BLU gateway or BLE proxy.

Last checked: 2026-03-23

Compatibility snapshot

Why it stands out

• very compact and inexpensive — easy to deploy on every door and window in the house
• long battery life thanks to Bluetooth Low Energy
• works locally through a Shelly BLU gateway or an ESPHome BLE proxy — no cloud involved

Reasons to hesitate

• requires a Shelly BLU gateway or ESPHome BLE proxy to reach Home Assistant — does not connect directly
• Bluetooth range is limited compared to Zigbee mesh or WiFi sensors
• no direct voice assistant integration without Home Assistant in the middle

Best for

• Home Assistant users with a Shelly BLU gateway who want cheap, reliable door and window sensors
• anyone building out a security or presence detection layer on a tight budget

Avoid if

• you do not have a Shelly BLU gateway or ESPHome BLE proxy and do not want to set one up
• you need long-range coverage — Bluetooth range is limited to roughly 10 meters indoors

Privacy and local-control notes

Bluetooth sensor with no cloud dependency. Data is transmitted locally via BLE to a gateway device. No internet connection needed for operation.

Home Assistant support: supported · integration path: via Shelly BLU gateway or ESPHome BLE proxy.

Built with ESPHome — see our ESPHome guide for Home Assistant →

Buying reality check

Price notes: One of the cheapest contact sensors on the market. The catch is you need a BLU gateway, but one gateway covers multiple sensors.

Compare side by side: see sensor comparisons →