sensor

Shelly BLU Door/Window

budget local: good Bluetooth

Price: $19.99 verified Sep 3, 2026
HA fit: good
Works offline: yes
Setup: easy
Hub needed: yes

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Shelly BLU Door/Window, a small Bluetooth contact sensor with its separate magnet

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 Bluetooth adapter on the Home Assistant host, or a Shelly Gen2+ or ESPHome Bluetooth proxy within range, 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.

Notes last checked Mar 23, 2026.

Compatibility snapshot

Home Assistant good

Apple Home none

Google Home none

Alexa none

Works offline yes

Setup easy

Extra hub needed yes

Power battery

Local control facts

Home Assistant: bthome integration, Local Push (home-assistant.io, checked Sep 10, 2026)

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

needs a Bluetooth receiver in range: the Home Assistant host's own adapter, a Shelly Gen2+ or BLU Gateway proxy, or an ESPHome Bluetooth proxy
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

your Home Assistant host has no Bluetooth adapter and you do not want to set up a Bluetooth proxy (an ESPHome node, a Shelly Gen2+ device or the Shelly BLU Gateway)
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: BTHome (official core integration, Local Push) via Home Assistant's Bluetooth integration: the host's own Bluetooth adapter, a Shelly Gen2+ or Shelly BLU Gateway Bluetooth proxy, or an ESPHome Bluetooth proxy.

Built with ESPHome - see the 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.

One verified price read so far: $19.99 at amazon on Sep 3, 2026.

Compare side by side: see sensor comparisons →

What changed for this product

Sep 7, 2026 · Corrected

Shelly follow-up audit and 16 more corrections

Six more Shelly products went through the same source check as the rest of the catalog. The Plus i4’s inputs are mains-level, not dry-contact (the DC model is the low-voltage one). The BLU Motion, BLU Button1 and BLU Door/Window pages no longer say a Shelly gateway is required: a Bluetooth adapter on the Home Assistant host or any Bluetooth proxy hears them directly. The Wall Display XL mounts to a standard switch box, and its dashboard claim now says exactly what Shelly ships: a Home Assistant page that loads a dashboard URL, deprecated and then restored in firmware 2.7.0. Five manufacturer links that had gone dead were replaced, the ZEN04 price was refreshed, the Tedee GO page names the official tedee integration as its non-Thread local path, and the G6 Instant page notes its IPX5 rating.

From the change log and the news briefs that name this product.