whatwatt is a Swiss company whose product is the whatwatt Go, a small adapter that plugs into the customer interface of an electricity smart meter and passes the readings to a network. Data is viewed in the whatwatt app, in partner apps such as myStrom and Solar Manager, or through the adapter's own web interface, REST API and MQTT client.
The whatwatt Go joins the home network over Wi-Fi (2.4 GHz) or Ethernet and reads the meter through ports such as P1, M-Bus or an optional Kamstrup HAN adapter. It is an energy-data device rather than a controller, so it has no voice assistant, Matter or hub role. Its smart home value comes from the data it exposes: a native Homey app, partner integrations, and a documented local REST API and MQTT client.
That suits households with a compatible meter, especially in Switzerland, who want live consumption and feed-in data in an energy app or in Homey. It is weaker for people who expect a ready-made Home Assistant or evcc integration, which we could not confirm, or who want to avoid licensing: whatwatt's manual says the REST API and MQTT services require a license, and the app lists paid licence tiers.
Connection
Wi-Fi 2.4 GHz or Ethernet; reads the meter through P1, M-Bus and similar ports
Voice assistants
None found
Matter
Not found
Open platforms
Homey app, local REST and MQTT; Home Assistant not confirmed
What can be connected
Smart meters Electricity meters with P1, HDLC/M-Bus or DLMS/COSEM customer interfaces, such as Landis+Gyr, Kamstrup, Sagemcom and Iskraemeco models
Energy apps The whatwatt app, myStrom (Power and Solar Actions) and Solar Manager
Smart home and data Homey Energy through the whatwatt Homey app, plus MQTT, REST and Modbus TCP access
The current app from whatwatt AG. It sets up the whatwatt Go on a compatible smart meter, shows meter data in real time and connects the meter to services. Release notes mention dynamic tariff prices, SolShare solar-sharing communities, linked accounts and licence management (Free, Plus, Pro, Cloud2Cloud and MAX). The store listing is in German, French, English and Italian and ends with the line Made for Switzerland. We found no Android listing.
An earlier listing with a similar description for installing the whatwatt Go and viewing meter data. The seller is shown as Vestiacom Prosta Spolka Akcyjna, not whatwatt AG, and we could not confirm how it relates to the current whatwatt app.
Official supported by the brandCommunity built by someone elseNot found searched, nothing foundUnconfirmed sources conflict or could not be opened
Platform
Status
What it means
Sources
Connection
Wi-Fi
Yes
The datasheet lists 2.4 GHz 802.11 b/g/n with WPA, WPA2 and WPA3, WPS and station or access-point mode, with an external antenna. myStrom's page says a constant Wi-Fi connection without WPA2-Enterprise or RADIUS is needed.
The adapter reads smart meters through P1 (RJ12), M-Bus, UART/TTL and RS232, with an optional adapter for Kamstrup Omnipower HAN. Protocols named include DSMR 4.x/5.x, HDLC/M-Bus and DLMS/COSEM.
The adapter sends its data to the myStrom app once the myStrom service is activated, which myStrom says needs a myStrom PRO subscription (CHF 11.90 per year on its page). myStrom Power and Solar Actions can then automate myStrom devices from the usage data.
The datasheet lists Solar Manager as a directly supported integration alongside whatwatt, myStrom, REST and MQTT. We did not open Solar Manager's own page.
We found no built-in Home Assistant integration or community add-on for the whatwatt Go. The datasheet says open-source smart home systems such as Home Assistant are available on request, and the adapter's MQTT client and Modbus TCP could in principle be used. We could not open Home Assistant's full integration list to rule out an entry.
A whatwatt app exists in the Homey store, listed as whatwatt AG Official, and Homey's newsletter says the Go now officially works with Homey, bringing live meter data into Homey Energy and Flows. The listing names Homey Cloud, Homey Pro, Homey Pro mini and Self-Hosted Server, but also says the device uses LAN and requires a Homey Bridge. Homey recommends the Go mainly for Swiss M-Bus meters and its own Energy Dongle where P1 meters are used.
We found no whatwatt page or evcc documentation naming the adapter, so support is unconfirmed. The adapter's REST, MQTT and Modbus TCP interfaces are the generic routes that other tools use.
The manual describes a REST API for settings and data and a built-in MQTT client that connects to a broker, configured through the API or web interface. Its front page says REST API and MQTT services require a license.
A third-party support guide says Modbus TCP is available from firmware v1.2.20, enabled through the settings API, with a register layout similar to the Siemens PAC2200. It is not covered in the datasheet or manual we opened.
Checked 11 November 2026 against the brand's own pages, app store listings and each project's own page. “Not found” means we searched and found nothing, not that it is impossible. Compatibility changes often. Spot an error? Tell us and we will fix it.
Common questions about whatwatt
Does whatwatt support Matter?
Not that we could find. No whatwatt Matter announcement or support found in the datasheet, manual or the pages we opened.
Does whatwatt work with Alexa?
Not that we could find. No integration found in whatwatt's datasheet, manual or app listing.
Does whatwatt work with Google Home?
Not that we could find. No integration found in whatwatt's datasheet, manual or app listing.
Does whatwatt work with Apple Home (HomeKit)?
Not that we could find. No HomeKit or Apple Home support found. The whatwatt app exists for iPhone but is an energy app, not a Home integration.
Does whatwatt work with Home Assistant?
Unconfirmed. We found no built-in Home Assistant integration or community add-on for the whatwatt Go. The datasheet says open-source smart home systems such as Home Assistant are available on request, and the adapter's MQTT client and Modbus TCP could in principle be used. We could not open Home Assistant's full integration list to rule out an entry.
Does whatwatt work with SmartThings?
Not that we could find. No SmartThings integration found when we searched.
Does whatwatt work with Homey?
Yes, officially. A whatwatt app exists in the Homey store, listed as whatwatt AG Official, and Homey's newsletter says the Go now officially works with Homey, bringing live meter data into Homey Energy and Flows. The listing names Homey Cloud, Homey Pro, Homey Pro mini and Self-Hosted Server, but also says the device uses LAN and requires a Homey Bridge. Homey recommends the Go mainly for Swiss M-Bus meters and its own Energy Dongle where P1 meters are used.
Does whatwatt work with Hubitat?
Not that we could find. No driver found.
Answers come from the sourced table above. See how whatwatt compares with all brands on the smart home brand statistics page.