I selfhost some tools and use duckdns for names resolution but it does not seem to be working today. My ISP updated some things on there end last night and I updated my local unbound server so I’m not sure which if either of these is also playing a role but I cant seem to access duckdns. I have tried to connect to it on my phone network outside of my isp’s control and cant which leads me to believe that duckdns is down?
deSEC.io is free and has an API. You can update your IP with a curl command. But you must bring your own domain.
They used to offer free subdomains on .dedyn.io but they had to stop because it was getting abused. 🙁