-
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.
https://github.com/samsquire/startups was listed in the "Ask HN: Those with money-making side projects,how did you come up with the idea?". It was not relevant there (the ideas are not money-making) but relevant to this question.
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.