I wonder if this uses P2P at all or whether everything is routed through their servers? The former would be far more sustainable (although NAT problems ahoy if that's the only channel).
It does look like they're planning on offering a paid version:
"Upgrade to Pro with end-to-end encryption to make your transfers completely confidential. We can't even access your files."
That's exactly right. We think most people will love the free tool for their personal use, and that many businesses will be willing to pay for End-to-End Encryption and CloudCache.
At first I believed that the revenue stream was like this:
1) ppl give their e-mail address
2) you scan the attachments (eg. words, subject etc).
3) you create a database
4) you sell the database to advertisers (that already have my e-mail address and can enrich their data).
It does look like they're planning on offering a paid version:
"Upgrade to Pro with end-to-end encryption to make your transfers completely confidential. We can't even access your files."