Is there any software, database or spreadsheet that can be used to keep a record of what cards you have etc? Obviously I could probably make one with excel or Google sheets but I thought it might be the kind of thing that already exists.

The Aurora squad building app!

Several different squad builders have this functionality so it can help you tell if you can build the squad with your current collection or not. Here are two that support it:

• https://geordanr.github.io/xwing/
• http://x-wing.fabpsb.net/gindex.php?lng=en

Awesome thanks guys!