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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.
There's also Ludusavi but I have no idea where it stores the backed up data (likely a centralized server)
I also wrote my own program to sync game saves to a SSHFS server but you have to manually create config files and own a server
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