Bip39 ledger https://www.storeboard.com/myrtierisaliti Abra - A mobile wallet that supports BIP39 seed phrases, supplying both of those wallet and exchange functions for cryptocurrencies. For words that only have three letters, there is not any 4th letter. For example While using the word “add”, there aren't any more letters Later on https://socialbraintech.com/story4971589/bip39-c-everything-about-bip39-word-list-txt-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw