With pinggy.io you can reach the SSH server on your machine from anywhere with just a single command. Replace the port 22 with the port where sshd is listening.
This is a TCP tunnel, so Pinggy gives you a host and port such as tcp://example.a.pinggy.link:11223 rather than an HTTPS URL.
From the remote machine, connect with the host and port Pinggy printed, dropping the tcp:// prefix:
ssh -p 11223 username@example.a.pinggy.link
For per-platform setup, see the SSH guides for Linux, macOS and Windows.