Seashells
seashells.io
What Jamie wrote
Huh, this is sort of whacky and geeky-cool.
Seashells lets you pipe output from command-line programs to the web in real-time, even without installing any new software on your machine.
I've used netcat a couple of times for some weird use cases, but turning that into something that you can use easily via the web seems interesting. I have no idea what I'd use it for though. 🤷♂️