-
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.
A famous book on Scheme that is introductory but theory-focused is Structure and Interpretation of Computer Programs. It's a large book with a lot of exercises. It literally starts from zero and slowly teaches you how to build a programming language with metaprogramming. A great resource for newcomers that are interested in some more theoretical aspects of programming rather than "making mobile apps".
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.