2026 verdict
The
Shelly 1 Gen4 is the newer and better equipped of these two single-channel Shelly relays, mainly because of its radios.
It adds Zigbee through a Zigbee hub to Wi-Fi and Bluetooth, acts as a Zigbee router, keeps Matter and Apple Home support, lists a 3-year warranty and idles at 1W. The
Shelly 1 Gen3 is the lower priced and better rated of the pair. Everything else carries over: the same 37 x 42 x 16 mm body, a 16A rating across resistive, inductive and capacitive loads, dry and wet contact modes, 110-240V AC power with a neutral or 12V / 24-48V DC power without one, and Alexa, Google Home, SmartThings and Home Assistant support. Choose the
Shelly 1 Gen4 for Zigbee or a mixed-protocol home, and the
Shelly 1 Gen3 for a Wi-Fi-only setup on a tighter budget.
What owners say
Owners of both generations praise the same things: a tiny relay that makes any circuit smart from behind the existing switch, dry contacts that handle garage doors and pumps, and local control that keeps automations running without the internet. Shelly 1 Gen3 owners single out wiring it into a ceiling box when the switch has no neutral, on-device scripting and ESPHome flashing, and a low-power mode for battery projects; their complaints are no energy monitoring, a tight fit and no push notifications. Shelly 1 Gen4 owners talk about choosing Zigbee or Matter, schedules that survive power cuts and detached mode for scene control, and they warn that it needs a neutral on mains power, like the Gen3, that Zigbee pairing on hubs like Hubitat is fiddly and underdocumented, and that some hit Android app problems.
Upgrading from the Shelly 1 Gen3?
Moving from the Shelly 1 Gen3 to the Shelly 1 Gen4 buys one real thing: Zigbee, with Zigbee routing, next to the Wi-Fi, Bluetooth and Matter the Gen3 already has. The size, the 16A rating, the dry and wet contacts, the AC and DC power options and the platform support stay the same, and so does the neutral wire both need on mains power. If your Shelly 1 Gen3 works on Wi-Fi, there is no reason to replace it; the Shelly 1 Gen4 is worth it for a Zigbee home.
