From another thread, an user asked for all the expansions that he doesn't own (for owned core games). BGG1tool can get that info, but the way isn't a straightforward one.
- insert the username in the "Load from user" field, and click that button.
- after the left list is filled, click the "Load games" button (that can take a long time, you can skip the images selecting before "Images" = None). In this case, 2248 games * 2s each= 1h 15m.
- when the center list is filled, click on "Expansions" button, that fills the left list with all the expansions from the games on the center.
- now, you must remove all the owned expansion: select the option "Sub" instead of "Rep" and click again on "Load from user" button (this action removes all the owned games from the left list).
- finally, when the last action is done, click again on the "Load games" button to obtain a list in the center with all the unowned expansions.
And at the end remember to re-set the "Rep" option instead of "Sub".
Games, software and BGG...
- [+] Dice rolls