Sending someone a big file shouldn’t need an account.
That’s the whole idea. The rest follows from it.
The problem
Most ways of sending a large file put a readable copy on someone else’s server. The company running it can open your files, and so can anyone who gets into that server. Many services also keep the files longer than needed, or want an account before anything can be sent.
What is different here
Your browser encrypts the files before anything is uploaded. The key is in the link, after the #, and browsers never send that part of an address to a server. The whole design leans on that one fact. Nobody needs an account, sender or recipient. A transfer is deleted after 24 hours at the latest.
What it does not do
It does not keep your files for you. Lose the link and they are gone, because the key was only ever in the link. It does not check what is sent either, since it cannot look. A transfer that is reported and breaks the rules is removed.
Who is behind this
A one-person company in the Netherlands, run by Robbert de Vries. There are no investors and no advertising, and nothing here is worth selling. A paid plan for people who need more is planned, to cover the costs.