Leave something. Close the tab. They find it tomorrow.
Every other app here needs everybody present at once — a whiteboard nobody is drawing on is nothing. This one is the opposite. You put an encrypted note or a small file in a channel and walk away; whoever has the link opens it whenever they like.
What it demonstrates
Encrypted channel storage used as a mailbox rather than a cache. Each drop is written with
storageAdd, so the channel keeps every one as its own version instead of a
single value people overwrite, and encrypted: true means the server stores
ciphertext it cannot read. The channel password is the key and it never leaves the browsers
that were given the link.
Nothing here is relayed peer to peer, because there is no peer. The store is the transport — which is exactly why it still works when you are the only person who has been online all week.
Read once
A drop can be marked read-once. Collecting it writes a tombstone rather than deleting anything, so the next person to open the box sees that it was taken and by whom — not what it said. A receipt is more useful than a gap, and honest about what a store can promise.
What it is not
Not a file host. Attachments are capped well under a megabyte, because a mailbox that quietly accepts a 20MB video is an unpleasant surprise for whoever opens it next. For real file transfer there is Drop, which streams peer to peer and never stores anything at all.