What are some alternatives?
When comparing Pearltrees and Tagpacker, you can also consider the following products
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Diigo - Diigo is a powerful research tool and a knowledge-sharing community
Pocket - When you find something you want to view later, put it in Pocket.
Pinboard - Pinboard is a personal archive for things you find online and don't want to forget.
Pinterest - Pinterest is a visual discovery tool that you can use to find ideas for all your projects and interests.
Papaly - Papaly is a simple social bookmarking tool to manage all your links.