What are some alternatives?
When comparing Raindrop and Diigo, you can also consider the following products
Atavi - Your bookmarks are always close at hand!
Pocket - When you find something you want to view later, put it in Pocket.
Cumulus - A SoundCloud player that lives in your menubar.
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
SoundNode - SoundCloud desktop app (OS X, Windows, Linux)
Pinboard - Pinboard is a personal archive for things you find online and don't want to forget.