Dev here! Happy to answer any questions.
Can I just say thank you so much for the detailed README! Even big professional projects sometimes are sometimes difficult to get a start with and understand with just the README. I was already familiar with FF Send but I feel like even if I wasn’t I would understand it deeply and know how to use it before I even cloned the repo.
And also the tool is awesome! I was definitely sad when Mozilla shut down their public one.
Thanks a lot for the wholesome comment! :)
How does this compare to Magic Wormhole?
Firefox Send is “async”. The file is uploaded first, then the server “buffers” it until the downloader comes by. This enables a nicer workflow but has some downsides (mostly server costs).
Magic Wormhole is Peer-to-Peer which removes the need for size limits and can have lower end-to-end latency and higher performance if both ends have a good connection (although it also means that both ends have to suffer if one end has a bad connection). But both users need to be online at the same time.
Wormhole is single-use, whereas Send can be accessed by several people without generating a new link.
Magic Wormhole has no size limits, which is nicer.
ffsend might be a little easier to use? Ymmv.