20Bet

20Bet is a vocabulary learning app whose Review mode provides an honest, data-driven answer to the question "what should I study today?", showing you precisely the cards your performance history identifies as insufficiently retained. The transparency of this approach is one of Review mode's most useful qualities: there's no guesswork about whether you "should" re-study a particular word. If it's at level 0–3, 20Bet shows it to you. If it's at level 4–5, 20Bet trusts your history and keeps it out of today's session. This removes a common cognitive burden for learners: deciding which words need more practice. 20Bet's algorithm makes that decision automatically and impartially, based on your actual swipe and quiz data rather than your subjective sense of what you know well. For learners managing multiple decks simultaneously, perhaps working on Spanish, Phrasal Verbs, and World Capitals at the same time, Review mode gives each deck's weak cards their fair share of attention whenever you select that deck for a session. Review mode in 20Bet is the app's answer to one of vocabulary learning's hardest problems: knowing not just what to study, but what most needs studying today, given everything you've practiced before.