SONOFF S40 Lite

Quick verdict

The SONOFF S40 Lite is a tinkerer's favorite. Out of the box it works with eWeLink (cloud), but flash it with ESPHome and you get a fully local energy-monitoring smart plug for pocket change. The 15A rating handles most household appliances. If you're comfortable with firmware flashing, this is one of the best value propositions in smart plugs.

Standout: ESPHome-flashable energy monitoring plug — go fully local with custom firmware.

Last checked: 2026-03-25

Compatibility snapshot

Why it stands out

• built-in energy monitoring with 15A capacity
• can be flashed with ESPHome for fully local, cloud-free operation
• very affordable for an energy-monitoring plug

Reasons to hesitate

• stock firmware is cloud-dependent via eWeLink
• ESPHome flashing required for best local experience
• build quality is adequate but not premium

Best for

• ESPHome enthusiasts who want a flashable energy-monitoring plug
• budget energy monitoring for individual appliances

Avoid if

• you want plug-and-play local control without flashing firmware
• you need Matter or Thread support

Privacy and local-control notes

Stock firmware uses eWeLink cloud by default. Can be flashed with ESPHome for fully local operation. The SONOFF LAN mode also provides some local control without flashing.

Home Assistant support: supported · integration path: sonoff_lan / ESPHome.

Buying reality check

Price notes: Very budget-friendly. One of the cheapest energy monitoring plugs available.

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