Ngrok alternative?

I currently have a 1.7.10 Spigot Minecraft Sever running over ngrok, so that a few colleagues can also use it. How about now with a better alternative (free of charge) to have the same IP that doesn't look completely random somehow.

If your Internet connection does not have a public IPv4 address, i.e. You can't use port sharing and then access the server with your IP (in that case you could work with DynDNS), you need ngrok or its alternatives. If you are not satisfied with the free plan, you just have to pay money.

Or you rent a VPS and work it out yourself with a VPN tunnel. But it's not necessarily beginner-friendly and then the question would be anyway, why not run the Minecraft server on it.