One of the most interesting of Copy is what they called Fair Storage. Basically they will equally divide the amount of storage being used. So a 12 GB folder shared between 3 people only counts as 4 GB per person. This is something interesting, as more and more people you shared with (assuming the same content), you will have more empty spaces.
They secure the data using top-secret grade AES 256 encryption algorithm which is proven to be highly secure.
They also offered the client apps in different platform, including Windows, Linux, Mac OS, Android, and iOS. For Slackware Linux, Eric Hameleers has provided binary packages on his repository.
What are you waiting for? Sign up now and if possible, use the above link :)