Steam nativaly integrated similar functions, as mentionned in this update; and removed the exposed API that was allowing this app to work. Bittersweet!
Depending on review time, there can be a discrepancy between the github version and the published version.
While the app is always up to date, it has a major caveat : it's using a glitch server to fetch data (and thus is slower and subjected to quotas). As a consequence, it cannot leverage the fact that a user is signed-in to steamcommunity.com to fetch private/friends profiles.
You can add users by their cosmetic ID (if they set-up one), steamID, or directly pasting their profile' URL in the add field.
Once you added a user (likely yourself), you can easily find your friends, or friends of friends using the friendlist button.
Also includes filters from Co-optimus, as well as size on disk!
:warning: Activating Co-optimus filters will greatly reduce the number of results, as data is available for "only" 2285 games. (airquotes as it is already a titanesque job since it's maintained manually)
A more flexible view showing more options by number of owners, instead of showing only exact overlaps. Quickly naviguate through groups using the shortcuts on the left. Fetch the price of games people of in your group don't own yet
The filters are using a dump from Steam & Cooptimus databases available here.
(More TBD)
Special thanks to @andrasfuchs whom feedback & support made this app better for everyone ^_^
And thanks to anyone in the Steam Community forums for their comments and suggestions.
This app is not affiliated, associated, authorized, endorsed by, or in any way officially connected with Steam or any of its subsidiaries or its affiliates.
The official Steam website can be found at https://store.steampowered.com/
This app is not affiliated, associated, authorized, endorsed by, or in any way officially connected with Co-optimus, or any of its subsidiaries or its affiliates.
The official Steam website can be found at https://www.co-optimus.com/