Bip39 Address To produce a seed phrase this way, You will need a calculator that has a RANDOM functionality (for making entropy). Find out more about building a seed phrase applying an offline calculator listed here. BIP39 specifies a list of 2048 words from which the mnemonic phrase is selected. https://directory-b.com/listings13030326/bip39-encoding-new-step-by-step-map-for-bip39