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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.
cc2530, CC2531, etc.: I found many using/reflashing these as gateways or routers and there is a repository of firmwares for that, but did not find anything about using them to build implement end devices (sensors/actors).
NOTE:
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Hence, a higher number means a more popular project.