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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.
This might not be exactly what you're asking for, but OpenStreetMap is "the Wikipedia of maps." It's quite comprehensive, easy to contribute to, and is not a revenue-generating private product.
For example OpenTopoMap looks very similar to most maps that were in my school atlas. I like the MapTiler renderings too.
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.