Whit Jackson made one which appears to become built employing HTML/Javascript (GitHub hyperlink). He also had a website where you could generate the addresses customer facet, but it appears for being down now. BTC addresses use Base58 (like Base64 but without very similar character: IOl0+/) and need to start with https://tron-address54310.idblogz.com/29797310/top-eth-vanity-generator-secrets