Bip39 wallet app https://gravatar.com/sparklyusually6089a4f337 Though it uses BIP32 technique you may even now import BIP39 seeds into Electrum wallet. Also aside from BIp32 There may be BIP44 version which some wallet use for that generation of seeds. For words that have only three letters, there isn't any 4th letter. As https://prbookmarkingwebsites.com/story25886146/bip39-hash-not-known-details-about-bip39-word-list-txt-https-x-com-tundra838554