It's the new fork
But I just wanted to ask him if he forked your tool or not.
I think he should give some credits to you.
I can't call it fork, coz it was done from scratch and i didn't do something with his codes, but the webpage looks was really inspired to his work.
I can't see the code of your api because your api is closed source. And although it is similar, the api is not what made me feel odd.
the balance Checker is definitely "a fork", it wasn't created from scratch. The code is terrible, i created it 4 years ago

I was still learning basic javascript.
But as I said, my website is now redesigned and I use a new code for this tool, with es6 js.
This tool is quite simple and I created this because I really needed It. I didn't find anything like it in the internet by the time (some didn't have segwit support, broken tools, etc).
I just hope bitmover wont change license now, like nvk did for coldcard wallet
Front end is always open source. I can't change the license of it...

Tools like the balance Checker , giveaway manager, unit converter, etc will always be open source.