Bip39 standalone https://writeablog.net/ipennywpzc/the-ultimate-overview-to-offline-bip39-generators-remain-secure Though it utilizes BIP32 approach it is possible to still import BIP39 seeds into Electrum wallet. Also besides BIp32 You can find BIP44 Variation which some wallet use with the technology of seeds. The amount of stability does a passphrase insert? A BIP39 passphrase sign... https://pukkabookmarks.com/story20882584/what-is-bip39-passphrase-the-definitive-guide-to-bip39-converter-https-dzen-ru-bip39-phrase-com