The design just meets my need as it seems to be inituitive,
but it doesn't work on my device for unknown reason. Maybe the API is dead I guess?
When the widget pop-up appearing, it prints "Your IP: \nDeveloped by China-cheats.com".
I suppose there should be my IP address, right? Somehow, it just leaves blank no matter how many times I tries.

@Windows 10 x64; Firefox Nightly 60.0a1
You may check the screen video below:
https://i.imgur.com/o6BguFu.gifv

I didn't use any proxy or VPN then.