Open system, private data.
It's not that other energy monitors are bad, but they are different in that they are mostly closed systems that provide limited data and require that you use their cloud and phone app platforms.  IoTaWatt collects many more metrics and stores that usage history locally.  With it's integrated web-server you can manage setup, view real-time status or create detailed graphs using the browser on your computer, tablet or phone. It's your data, in your own home, and subject only to your own privacy and retention policy. You don't need the cloud to get a handle on your hot-tub, EV, solar or heat-pump.

IoTaWatt can, however, easily upload usage data to any of several third party databases with associated apps and analytic tools.  For instance PVoutput is a free service that connects easily with IoTaWatt and provides world-class solar energy analytics. There is full support for uploading to influxDB.  There is also an API interface for those who want to query data for their own applications or to use in spreadsheets, and there are integrations available for home automation software like Home Assistant.

A universal solution.
IoTaWatt is probably the only monitor in it's class that can literally be used to monitor any power system.  It is in use in over 60 countries worldwide.  USA split-phase 120V/240V is easy, but also 230V single-phase as in Europe, 230V three-phase as in homes in Australia, Germany and norway to name a few. Most folks only care if it will work in their situation.  The answer is an unqualified yes.

There are also many commercial/industrial users monitoring high voltage three-phase systems including 277V/480V industrial with 600Amp service using several megaWatt-hours per day - more than most households use in a year.