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Specifically with the Spotify service, the problem with the Spotify API is that you can only request listening data for the last 100 played songs iirc. You can manually request the data from Spotify, but it will take them a month or two to give you the data and it will be a snapshot of it.

So if you want live updates on statistics about your listening habits you need a service running 24/7 querying the Spotify API and storing the information in a database. Assumedly since most people don't have a computer to run this on 24/7, a server is necessary / preferred.

I've actually written an application doing something similar, it's very annoying that Spotify's API works like this.