Why would anyone use this service when you can just transfer files by temporarely opening a TCP port and starting a netcat listener that you pipe into the file you want? It's as simple as nc -lvnp 1234 > myfile.txt
The other party then only needs to pipe the file into a netcat socket from their commandline. nc -w 3 IP
Jokes aside I'm intrigued at the "no server involvement". I'm assuming they mean the file isn't transferred through the server but directly (WebRTC?). There is probably still some server involvement to get around the firewalls / NAT. I don't think this will work if you just host your own instance of it.