Peer-to-peer file transfers in your browser Cooked up by Alex Kern & Neeraj Baid while eating Sliver @ UC Berkeley.
Using WebRTC, FilePizza eliminates the initial upload step required by other web-based file sharing services. When senders initialize a transfer, they receive a "tempalink" they can distribute to recipients. Upon visiting this link, recipients' browsers connect directly to the sender’s browser and may begin downloading the selected file. Because data is never stored in an intermediary server, the transfer is fast, private, and secure. (Your PC must be online while the recipient download the file(s), if you shutdown the PC or goes offline, the download also stops)
You can selfhost it or use the official instance
https://github.com/kern/filepizza
I created my own similar tool: https://filepush.kevincox.ca/
It is optimized for the case where you commonly send files to the same devices. For example I have set up all of my devices as well as my partner's phone and Steam Deck. Then I can just tap them and send the file with end-to-end encryption.
It is sort of cool that there is no backing server, just static files. All of the signalling goes over WebPush.