Bip39 Seed Generator. The passphrase just isn't chosen through the predefined list of 2048 words – it could be any word or phrase you select. BIP39 is usually a layout implementation that lays out how copyright wallets produce the list of words (or "mnemonic codes") that make up a mnemonic https://thebookpage.com/story4230360/bip39-word-list-pdf-https-linktr-ee-bip39-not-known-details-about-bip39-list