How do you avoid buying CD's you already have?

[CatManDo]

I use a Whereisit database for all my content, with catalogues separated by content type (music, movies, ebooks). It scans hard drives, data discs, DVDs, etc and imports the content into a searchable database 

 

https://www.whereisit-soft.com/

 

So when I search my collection for an album, I get a result if I have it on CD or on files, even with LPs that I have added manually.

 

The content of a database can be exported to text files, which I keep on my smartphone (to use with a search in text function). But I actually no longer need that, as I've stopped going to physical stores.

 

The software is no longer being maintained, but it's still the best. There are clones, which are not that great (much slower scanning or searching).