Hello!
I wrote a small tool to convert Bitcoin addresses to Bitcoin Gold ones.
Just enter your Bitcoin address to see the corresponding BTG one, along with a block explorer link to quickly check the balance.
It also works vice-versa, you can convert BTG addresses to BTC too!
SegWit and multisig addresses are supported experimentally.
It's hosted on GitHub Pages
here.
Source code: https://github.com/SopaXorzTaker/gold-address
Uses the bs58check library, by bitcoinjs (MIT).