01
Decision trainer
Instant feedback on every hand
Train hard totals, soft totals, pairs, doubles, and surrenders against the chart for your rules. Wrong plays come with the reason, not just a red X.
iPhone · Free to start
Make the right move. Every hand.
Blackjack trainer for basic strategy, table-rule variants, and Hi-Lo counting.
Basic strategy
Hi-Lo counting
Made for iPhone
Hi-Lo countingFlash, running count, ramp
Instant feedbackLearn every decision
A better way to learn
Practice built around real decisions.
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Curriculum
40+ lessons, in order
Fundamentals through pairs, advanced edge, and Hi-Lo. Quizzes and chart highlights so the math sticks beside the muscle memory.
03
Card counting
Flash, running count, ramp
Build speed with Hi-Lo recognition, hold a running count through timed sequences, then let Ramp Mode push the pace.
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Reference
A chart that matches your table
Color-coded basic strategy for H17/S17, DAS, and surrender. Tap any cell for the recommended play and why it wins more often.
The TwentyOne journal
Strategy, explained without the noise.
count cards online blackjack
U.S. Online Blackjack: About 50% Penetration Erases the Counting Edge
No, you cannot practically count cards in RNG online blackjack, because the virtual deck is reshuffled after every hand. Live-dealer streams are technically countable, but shallow penetration,
Table rules
Blackjack Hand Signals: Hit, Stand, Double, Split & More
Learn the hand signals used at live blackjack tables, including hit, stand, double, split, and surrender. Understand face-up versus face-down games and avoid common casino mistakes.
blackjack tournament strategy
Blackjack Tournament Strategy: Drill Final Bets on the Clock
Blackjack tournaments are betting contests, so conserve chips early, use a progression in the middle rounds, and plan your last-hand bet before the round starts. Stanford Wong’
Table rules
Blackjack Rule Variations: Which Table Rules Matter Most?
Blackjack rules are not equally important. Learn how 3:2 vs. 6:5, S17/H17, DAS, surrender, deck count, splitting, and hole-card rules change the value of a table.
Table rules
Free Bet Blackjack Explained: Rules, Strategy & House Edge
Free Bet Blackjack lets the house fund qualifying doubles and splits, but dealer 22 pushes instead of busting. Learn how the free bets work, why strategy changes, and what the tradeoff costs.
Basic strategy
How to Play Blackjack: Rules, Actions & Beginner Basics
Learn how a blackjack round works from placing your bet through the dealer’s final hand. This beginner guide covers card values, player actions, payouts, table rules, and the mistakes to avoid before you play.
Questions
Before you download.
Straight answers about the trainer, basic strategy, and what is included.
Is TwentyOne real-money blackjack?
No. TwentyOne is an educational trainer only. There is no wagering, no chips with cash value, and no connection to any casino or sportsbook.
What is basic strategy?
Basic strategy is the mathematically best play for every starting hand against every dealer upcard. It tells you when to hit, stand, double, split, or surrender so the house edge stays as low as the rules allow.
Does basic strategy guarantee a win?
No. Correct basic strategy reduces the house edge; it does not remove it. Short-term results still swing with variance, which is why the app focuses on decision quality, not session outcomes.
Can I match the rules at my casino?
Yes. Set H17 or S17, double after split, and late surrender so the strategy chart and decision drills match the plaque on the table you actually sit at.
What is Hi-Lo card counting?
Hi-Lo assigns a value to each card (+1, 0, or −1) so you can track whether the remaining shoe favors the player. TwentyOne teaches recognition, running count, and speed drills — not a shortcut to guaranteed profit.
What is free vs. premium?
Module 1 — fundamentals and your first drills — is free. Premium unlocks the full curriculum, unlimited decision practice, Hi-Lo counting modes, and detailed session stats. Monthly, annual, and lifetime plans are listed on the App Store.
Can I practice offline?
Yes. Lessons, the strategy chart, and practice sessions work without a connection. Progress stays on your device until you choose to back up through iCloud.
Which devices are supported?
TwentyOne is built for iPhone. It runs on any device that meets the current App Store requirements for iOS. There is no Android or web version today.
TwentyOne on iPhone
Drill the play until it is automatic.
Instant feedback on every decision, a full basic-strategy chart for your rules, and Hi-Lo drills when you are ready to count.
