It appears that you can get an https certificate (TLS cert) for a webserver, that could be on a random vps or home connection, without needing your own domain,

It appears that you can get an https certificate (TLS cert) for a webserver, that could be on a random vps or home connection, without needing your own domain, using this and lets encrypt. Though there is a risk of it failing due to rate limiting at Lets Encrypt if lots of people do that. There is always the risk that whoever is running this service will switch it off one day. There was a similar service called xio.io that stopped working then the man running it got a new job. There is also http://traefik.me/ http://traefik.me/ and sslip.io which offer more-or-less the same service. There is https://ipq.co/ https://ipq.co/ and https://fdns.uk/ https://fdns.uk/ which will give you a name pointing at an ip of your choice.