Localhost tunneling has existed for a long time. It's great if you're already doing it somehow. The benefit of Vagrant Share is that it detects all these ports for you and is basically zero-touch: "vagrant share" and you're done!

Another benefit Vagrant Share has that I haven't seen yet in any other localhost tunneling solution is that it shares _every_ port (if you want), not just a single port, and gives the other person an IP to access the machine as if it were on the LAN. This is super nice if you want to expose anything like Redis, SSH, etc. You just "vagrant share" and, again, you're done.

Also, many localhost tunneling solutions don't support UDP. We fully support UDP connections in addition to TCP.

The big win, though, technology aside, is how if you use Vagrant, this just becomes another part of your Vagrant workflow that _just works_. You don't have to worry about installing anything, and of course it'll work with any sort of guest machine running on any provider.