Beeline lets you share your clipboard among web-enabled devices (PCs, smartphones, tablets). The objective is to make Ctrl-C Ctrl-V work as transparently as possible across devices, just like it does now on the same machine.
Only web interface is envisioned currently. It's ubiquituous; and it doesn't take a ton of time to implement a web app that works everywhere.
Clojurescript
Clojure
The transfer should be peer-to-peer to avoid storing much of anything on a server.
Web RTC seems like an obvious choice here, unless another viable peer-to-peer tech is possible (IPFS?)
We'll start with local connection, then adding trickle ICE and STUN server to improve discoverability/connectivity.
Since TURN would add significant complexity and operation cost, it's lowest on the priority list.
A good high-level overview: https://webrtcglossary.com/stun/