-
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.
Their website is https://syncthing.net/ and there are youtube videos that do a good job explaining it and showing you how to set it up. I recently set it up to automatically download all my photos off my phone, and it also backups of all the computers in the house.
For an example program, look at duplicacy, https://duplicacy.com/.
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.