Bip39 is not defined https://www.tumblr.com/generalllamacolor/787594721599078400/can-you-depend-on-online-bip39-generators-a Regardless that it works by using BIP32 technique you are able to however import BIP39 seeds into Electrum wallet. Also aside from BIp32 there is BIP44 Model which some wallet use for that generation of seeds. Mainly because adding a passphrase for your seed words https://mediajx.com/story26285706/bip39-random-word-generator-not-known-details-about-bip39-word-list-txt-https-linktr-ee-bip39