Put two collections side by side to see exactly what each one could trade the other. Pick one of yours for each side, or paste a friend's share code.
Send them a compare link: it opens this page with your collection on one side and theirs on the other. No account needed.
Supporters can share a live link instead — one link that always shows their current collection.
Two versions of your collection
This device and your synced copy have both changed since they last agreed. They can't be merged safely, so pick which one to keep — the other is replaced.