-
InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
Mestastic has been doing fine work. I'm not a fan of the CLA though.
MySensors, IM(very)HO is a better system if you are building your own gear. They too have CLA requirements.
https://www.mysensors.org/
NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a more popular project.