TwentyOne: Blackjack Trainer

TwentyOne is a clean, focused blackjack basic-strategy trainer. Learn the mathematically correct play for every hand, then drill it until it's second nature — in a calm, minimalist interface with no ads and no clutter.

WHY TWENTYONE Basic strategy is the proven, optimal way to play every blackjack hand. TwentyOne doesn't just show you a chart — it computes the correct play for your exact table rules and helps you commit it to memory through fast, focused practice.

THE STRATEGY CHART • The complete chart for hard totals, soft hands, and pairs • Color-coded for Hit, Stand, Double, Split, and Surrender • Tap any cell to see the expected value behind every option • Recomputes instantly when you change the rules

PRACTICE THAT STICKS • Deal a hand, choose your action, and see the correct play right away • Modes: Random, Hard Totals, Soft Hands, Pairs, and Most Missed • "Most Missed" automatically resurfaces the hands you get wrong • Track your accuracy, streak, and performance by hand type

PLAYS BY YOUR RULES Real tables differ, and so does correct strategy. Configure: • Number of decks (2, 4, 6, or 8) • Dealer hits or stands on soft 17 (H17 / S17) • Double after split, double rules, and late surrender • Resplit aces, hit split aces, and more The chart and every practice answer adjust automatically.

TWENTYONE PRO Take your training further with a single one-time purchase — no subscriptions, no ads: • Expected value on every hand — see the full EV breakdown behind your decision after each practice hand, not just in the chart • Card Counting Trainer — master the Hi-Lo system with four focused drills: – Card Values: flash through the +1 / 0 / −1 tags until they're instant – Running Count: keep an accurate count as cards are dealt – Deck Countdown: race through a full deck down to zero – True Count: convert running count to true count on the fly

Everything else in TwentyOne is free.

MADE TO LOOK GOOD • Minimalist design with crisp, simple cards • Full light and dark mode • Three app icons to choose from • No ads, no accounts, no tracking — works offline for all training

TwentyOne is for study and entertainment. It teaches optimal decision-making and involves no real-money play and no wagering.