WebWormhole: WebRTC encryption, direct data transfer, large file support, browser and command line. Looks more versatile than the others. Has not undergone security review yet.
https://github.com/saljam/webwormhole
Magic Wormhole: Data relay required (public relay is often slow), mainly command line.
https://github.com/warner/magic-wormhole
https://magic-wormhole.readthedocs.io/
croc: End-to-end encryption, data relay required (I think), command line only.
https://github.com/schollz/croc
https://schollz.com/blog/croc6/
File Pizza: WebTorrent, seems to load entire file into RAM, browser only.
https://github.com/kern/filepizza
Snapdrop: WebRTC encryption, local sharing only (I think), browser only.