Exact expected-value engine
For every hand and dealer card it works out the value of standing, hitting and doubling. The dealer's final-total distribution is computed by memoised recursion, and hitting recurses until standing is better.
TestFlight beta · iPhone · US only · 18+
Blackjack has a right answer.
Upcard teaches it. A full course, drills that grade every answer, a practice casino with real rules, and a coach who reads your play and tells you what your mistakes cost. Practice only: no real money, ever.
Formerly “Blackjack Mastery.” If the beta link says it's full, email upcard21@gmail.com and I'll add you.
47
lessons in 13 tiers
340
chart hands, each graded
7
drill modes
8
games and tables
1,265
automated tests
$0
real money, ever
How it works
Learn it, drill it, play it, prove it.
Blackjack is one of the few casino games with a known best play for every hand. That makes it learnable, like a chess opening. Upcard runs one loop until the right play is automatic.
- 1
Learn
A short lesson deals you real hands. You choose, then see why.
-
2Drill
Timed questions on the chart. Every answer is graded against the maths.
- 3
Play
Sit at a practice table. Every decision you make is checked.
-
4Get coached
Ace finds the mistake you repeat most and tells you what it costs.
- 5
Prove it
Four measured checks. Clear all four and basic strategy is yours.
Under the hood, every answer does four things.
1. It is graded by the engine.The right play comes from exact EV maths for your table rules, never from typed-in text.
2. It is logged with detail.Which hand, what you chose, what the book says and how long you took.
3. It updates your plan.Misses go into spaced review. Your gate checks, rating and tomorrow's steps recompute.
4. It feeds the coach.Ace groups repeated misses and prices each one by the money it would lose per bet.
Try it right here
Three hands. What would you play?
Six decks, dealer stands on soft 17. Each hand has one correct answer. This is the same decide, grade and explain loop the app runs.
Hand 1 of 3
What you get
Everything in Upcard.
Nine parts, each captured from the current beta build. Nothing below is a mockup.
Today
One screen that tells you what to do next.
- Basic Strategy card. Your four mastery checks and your accuracy over the last 200 answers, live.
- Three steps a day. Lesson, Review and Practice, picked for you. Done steps close until tomorrow.
- Ace noticed. Your most costly repeated mistake, with a one-tap drill to fix it.
- Quick actions. Look up any hand, ask Ace, and see your streak.
- Trip row. Counts down to a casino trip you set, then asks how it went.
Learn
A full course, from the rules to the maths.
- 47 lessons, 13 tiers. About 3.6 hours in all, from "what is blackjack" to bankroll risk.
- Three kinds of lesson. Hands (you play the hand), Counting (you keep the count) and Reading (one idea per page).
- Answers come from the engine. A lesson cannot teach a play the maths disagrees with.
- Search and filters. Find any lesson or idea. Your place is saved mid-lesson.
- Placement quiz. Already know the game? Eight questions skip you ahead.
- Reading level. Short or full lessons, in simplified, standard or technical language.
Drill
Practice that grades every answer and shows the working.
- Seven modes. Mixed, Chart, Counting, Deviations, Weakest link, Memorise and Hand reading.
- Shot clock. 5 seconds per decision, 7 for typing. Running out counts as a miss.
- EV bars. After each hand: what every play was worth, under your table rules.
- Chart fill. Fill a whole section of the chart. Only the cells you miss come back.
- Spaced review. Missed hands return on a schedule until they stick.
Ace, your coach
A coach who reads your practice, not a script.
- Names your top mistake. How often you make it and roughly what it costs per bet.
- Tap replies. "Why?", "Give me a rule", "How am I doing?", "What's next?" Built from your own log, no AI needed.
- AI explanations. "Explain it another way" and "A trick to remember it".
- Ask anything. Type a question about your play. Ace answers from your own chart and history.
- Notebook. Answers, accuracy, streak, freezes and your weak spots in one place.
The Cut
A small practice casino with real table rules.
- Three tables. The Parlor (6 decks, 3:2), Solo Deck (1 deck) and Tourist Trap (6:5, dealer hits soft 17).
- Twelve-hand shifts. Computer players at the table, a real depleting shoe, a cut card.
- Your settings. Number of players, auto re-bet, and deal speed from normal to instant.
- Practice table. A bankroll that carries over and a coach that shows the book play and its value.
- Points, not money. Every chip is pretend. Nothing to buy.
Train
Five quick games for the reps.
- Today's Table. One shoe a day, the same for everyone. Ten hands, one try.
- Count Race. Tag 20 cards against a ghost of your best run.
- Count Sprint. Cards flash faster as you improve. Keep the count in your head.
- 21 Rush. Strategy calls against a clock that speeds up. Three lives.
- Quick Bite. Ten hands in about 90 seconds. Also saves a broken streak.
- Beat the clock. Speed Round, Illustrious 18 Gauntlet, Marathon and Tough Table.
Progress
Effort and skill, measured separately.
- XP and levels. XP is effort, with daily caps so grinding does not count. Titles from Rookie to Legend.
- Strategy rating. Skill only: recent accuracy and speed. Chip colours from white to gold.
- 39 badges. Learning, practice, consistency, chart, table and real-world groups.
- Streaks and freezes. Freezes cover a missed day. One missed day can be repaired.
- Table felts. Six felt colours unlock with level. Looks only.
Before and after a trip
Get ready away from the table.
- Trip Prep. Set a date. See how ready each part of the chart is and drill your shaky hands.
- Trip planner. Bankroll, hours and bet size in; a simulated range of results and the chance of going broke out.
- Trip log. Record real sessions afterwards: buy-in, cash-out, hours and rules.
- Never at the table. All of it is before or after. Using a device at a live table is a crime in many states.
Cheat sheet
The whole chart, made for your table.
- Five sections. Basics, Chart, Counting tags, Index plays and Study notes.
- Generated live. Built from your table rules by the engine, so it always matches the drills.
- Mastery map. All 340 hands coloured by how well you know each one.
Ten minutes is enough to see if it's for you.
Free on TestFlight. No account needed to start.
Who it's for
Built for people who'd rather know than guess.
The occasional player
You play a few times a year and want to stop guessing on 16 against a 10. Basic strategy, learned properly, in short daily sessions.
The one with a trip booked
Set the date. Trip Prep shows which hands are still shaky and drills exactly those before you go.
The curious mind
You want the why: expected value, the dealer's odds, counting, risk of ruin. The course goes as deep as you like.
Not for
Anyone looking for a way to make money. Upcard will tell you plainly that it isn't one.
The complete list
Every feature, on one page.
Learning
- 47 lessons in 13 tiers
- Hands, Counting and Reading lessons
- Placement quiz
- Short or full lessons
- Simplified, standard or technical language
- Search and filters
- Resume mid-lesson
- First-hand walkthrough on install
Practice
- 7 drill modes
- 5-second shot clock
- EV bars after every hand
- Chart fill by section
- Spaced-repetition review
- Illustrious 18 and Fab 4 index plays
- Hi-Lo, KO, Omega II, Wong Halves
Play
- The Parlor, Solo Deck, Tourist Trap
- 12-hand shifts with computer players
- Practice table with a coach
- Today's Table (daily seeded shoe)
- Count Race, Count Sprint
- 21 Rush, Quick Bite
- 4 timed challenge sets
Coaching
- Ace: top mistake, priced per bet
- Tap replies from your own data
- AI "explain it another way"
- AI "a trick to remember it"
- Typed questions to Ace
- Notebook: weak spots and streak
Progress
- 4-check basic strategy gate
- Strategy rating (chip bands)
- XP, levels and titles
- 39 badges, bronze to gold
- Streaks, freezes and repair
- 6 unlockable felts
- Mastery map of 340 hands
Tools
- Cheat sheet for your rules
- Trip Prep countdown and shaky hands
- Trip planner (Monte Carlo)
- Real-session trip log
- Table rule presets
- Unit size setting
Everyday
- Daily plan that renews at midnight
- Smart local reminders (no server)
- Sounds and haptics
- Works fully offline
- Sync across devices
- Sign in with Apple, Google or email
Safety and privacy
- Practice only, no purchases
- 18+ and US only
- "Never at a table" warning
- Anonymous analytics, opt-out
- Delete your account in-app
- Gambling help links
Free, no account
Tiers 0 and 1 of the course, your first hand, The Parlor, Quick Bite, 21 Rush, Trip Prep and the trip log.
Free account
Everything else: all 13 tiers, Drill, every table and game, the practice table, the planner, Ace, and sync across devices.
The knowledge
The course: 13 tiers, in the order the maths builds.
From how a hand works to bankroll risk. Basic strategy is the core; counting and deviations come after it, and the honest limits come at the end.
- Tier 0
Orientation
What the game is, and an honest promise about what this app can and cannot do.
- Tier 1
The table
One full hand, start to finish: push, blackjack and reading your own hand.
- Tier 2
Table craft
Buy-in signals, rule variants that change the maths, and the ten-second scan for traps.
- Tier 3
Basic strategy
Hard, soft, pairs and surrender. Twelve rules to understand and a short list to memorise.
- Tier 4
The maths beneath
Expected value, built by hand: the dealer machine, doubles, splits.
- Tier 5
Counting: Hi-Lo
Three tag values, running count to true count, at table speed.
- Tier 6
Other systems
KO, Omega II and Wong Halves, and why most people should stay on Hi-Lo.
- Tier 7
Deviations
Insurance first, the established index plays, and when not to use them.
- Tier 8
Bankroll and risk
Kelly betting, risk of ruin, N-zero, and noise versus signal.
- Tier 9
Staying welcome
What the pit watches, cover play and the back-off.
- Tier 10
The line
Shuffle tracking, team play and the line you do not cross.
- Tier 11
Reference
Blackjack variants, online play, taxes and the myths worth unlearning.
- Tier 12
Graduating
What this actually pays, who it is for, and what you own once you are done.
The part most apps leave out
It tells you the unflattering number.
Perfect basic strategy does not beat the house. It shrinks the house's cut. The app says so, and shows how much the rules on your table matter.
0.57%
The Parlor
House edge with perfect play. 6 decks, 3:2, dealer stands on soft 17.
2.14%
Tourist Trap
Same perfect play. Blackjack pays 6:5 and the dealer hits soft 17.
Both figures come from the app's own engine. The worse table costs almost four times as much, with no change in how well you play. Only correct counting can tip the edge to the player, and even then it is thin and shows only over tens of thousands of hands.
"Mastered" means something specific. 1,000 decisions, 97% right over your last 200, under 5 seconds on average, on at least 3 different days. All four at once, and it slips back if you get worse.
S stand H hit D double P split R surrender
The AI engine
Ace explains. The maths decides.
The AI never chooses the right play. A deterministic coach finds the mistake, the chart is handed over as the answer key, and the model's only job is to put it in plain words.
1
Your answers
Every graded decision, with the hand, your choice, the book play and your time.
2
Diagnosis
Pure code groups repeated misses and prices each by EV lost per bet.
3
Summary
Gate progress, top mistakes, weak topics, your rules and your full chart. No name, email or money.
4
Edge Function
Checks the account, takes a slot from the daily cap, calls Claude with a server-side key.
5
Reply
Short, labelled "The chart is the final word", with a Report link.
Two models, two jobs
- Claude Sonnet 5.5Typed questions. Up to 300 characters in, about 380 tokens out. System prompt is prompt-cached; the last few turns are sent for context.
- Claude Haiku 4.5"Explain it another way" and "A trick to remember it". Replies are saved on the phone, so asking twice costs nothing.
Guardrails
- Hard caps5 replies per person per day, 100 per 30 days, 2,000 per day across everyone. A failed call refunds the slot.
- No anonymous useThe server refuses guest accounts.
- Tap replies need no AI"Why?", "Give me a rule", "How am I doing?" and "What's next?" are built from your log on the phone.
Evaluated, not trusted
- CheckerRejects replies that invent statistics or contradict the chart.
- 15-case evalGates every prompt change. First live run 8 of 15; after tightening, 14 of 15.
- Fails gracefullyOffline or capped, Ace says so plainly. The rest of the app does not depend on him.
The algorithms
Eighteen pieces of maths and logic, all on the phone.
Pure TypeScript, no server, each one covered by tests. Where a model is an approximation, the code says so.
Strategy chart generator
The chart is the best action per cell under your rules (decks, soft 17, payout, double and surrender rules). Change a rule and the chart, lessons and drills change with it.
Split EV
Models one split: two hands, one new card each, played out normally. Resplits are a documented simplification; every published split decision still comes out right.
House edge
Sums the EV of every two-card start against every dealer card, then adds back the dealer-blackjack branch at its true probability. The Parlor: 0.57%. Tourist Trap: 2.14%.
A real shoe
The tables deal from an ordered, depleting shoe: Fisher-Yates shuffle, a cut card at the set penetration, no replacement until the reshuffle. That is what makes counting mean something.
Counting and true count
Four systems (Hi-Lo, KO, Omega II, Wong Halves) with their own tags. True count is the running count divided by decks left, estimated from the discard tray.
Index plays
The Illustrious 18 and the Fab 4 surrenders: the true counts where the right play changes, ranked by value.
Spaced repetition
A simplified SM-2, the method Anki uses. A miss comes back now and lowers its ease; a hit comes back in 1 day, then 6, then the last gap times the ease.
Mastery gate
1,000 decisions, 97% over your last 200, under 5 seconds on average, on 3 different days. Recomputed from history every time, so it can slip if you get worse.
Mistake diagnosis
Groups your misses by situation (for example "hit a stiff against a weak card"), counts them, and prices each by the EV it lost, in cents per dollar bet. Worst first.
Strategy rating
80% recent accuracy, 20% answers inside the 5-second budget, scaled by how much evidence there is, so ten lucky answers cannot make a high rating.
Kelly betting
Bet sizing as edge divided by variance (about 1.3 units² per hand), with fractional Kelly because full Kelly is too swingy for real people.
Risk of ruin
The Wald diffusion approximation, exp(−2 · edge · bankroll / variance), shown next to the simulator's own count of how often a bankroll went broke.
Monte Carlo trip planner
Simulates many trips hand by hand from the house edge and per-hand variance to give a realistic range of results, not one number.
Daily seeded shoe
Today's Table hashes the date with FNV-1a and shuffles with mulberry32. Everyone gets the same cards on the same day, with no server.
Sync merge
Answers are combined and de-duplicated, review items keep the copy scheduled furthest out, and a default never overwrites a saved setting. Pushes retry from 30 seconds up to 10 minutes.
Reminder planner
Plans two weeks of local reminders from your habits: at most one a day, at the hour you usually practise, never on a day you already did.
Derived progress
XP, levels, badges and rating are worked out from your answer history every time, never stored as totals, so they cannot drift or be corrupted.
Tech specs
The facts.
- Platform
- iPhone, portrait. iOS 16.4 or later.
- Status
- TestFlight beta, version 1.0.0. US only, 18+.
- Price
- Free beta. No in-app purchases, no ads.
- Account
- Optional. Guests get the first two tiers, The Parlor, Quick Bite and 21 Rush.
- Offline
- Everything except sign-in, sync and Ace's AI works with no network.
- Default rules
- 6 decks, dealer stands on soft 17, blackjack pays 3:2. Change them in Settings.
- Counting systems
- Hi-Lo, KO, Omega II, Wong Halves.
- Content
- 47 lessons, 13 tiers, about 3.6 hours. 340 chart hands. 39 badges.
- AI models
- Claude Sonnet 5.5 for typed questions, Claude Haiku 4.5 for explanations.
- AI limits
- 5 AI replies per person per day, 100 per 30 days. Optional; the app works without it.
- Data
- Progress on the phone; a synced copy for signed-in players. No name or email sent to the AI.
- Analytics
- Anonymous (random device id). Off by default in the EU, UK and Switzerland.
- Notifications
- Local only, no push server. At most one a day.
- Built with
- Expo SDK 57, React Native 0.86, React 19, TypeScript, Supabase.
- Quality
- 1,265 automated tests in 76 suites, run on every push.
The stack
Everything it takes to ship an app, picked on purpose.
One person, one codebase, one cloud project.
App
- Expo SDK 57 + React Native 0.86New architecture, React 19, one TypeScript codebase.
- expo-routerFile-based routes, deep links and typed navigation.
- Context + reducer storeOne predictable state, sanitised and versioned on the phone.
- react-native-svg, ReanimatedCharts, felt tables, cards and chips drawn in code.
- expo-audio, expo-hapticsSoft sounds that respect the silent switch, Taptic feedback.
Engine
- Pure TypeScript mathsEV, house edge, counting, index plays, Kelly, risk of ruin, Monte Carlo.
- Seeded RNGmulberry32 + FNV-1a for the shared daily shoe.
- Coach and plannerMistake diagnosis, SM-2 review, daily plan, reminder plan.
Backend
- SupabasePostgres with row-level security, Auth (Apple, Google, email), Deno Edge Functions.
- Merge syncOne progress record per player, merged on both sides, 5 MB cap.
- Claude APISonnet 5.5 and Haiku 4.5 behind a server-side key, per-user and global caps.
Quality
- Jest, 1,265 testsEngine maths, a 28-day simulated player, sync merges, every app link resolves.
- AI evalA checker and 15 cases gate any prompt change.
- GitHub ActionsType check and tests on every push, plus a backend keep-alive.
Observability
- SentryCrash and error reports, no personal data attached.
- PostHogAnonymous events, batched, opt-out in Settings.
Shipping
- EAS Build, Submit, UpdateTestFlight and production profiles, over-the-air updates.
- Release gateBlocks an App Store build until the legal fields are complete.
- VercelPrivacy and support pages.
- Built with Claude CodeAI pair programming, every change reviewed and tested.
How it fits together
Offline first. The cloud is a backup, not a dependency.
The craft
Where the interesting problems were.
The chart is computed, not copied
Hit, stand, double and split values come from the EV engine for the rules you pick. Lessons and drills are tested against it, so the app cannot teach a play its own maths disagrees with.
An AI coach on a leash
The model never decides the right play. The deterministic coach finds the mistake and the chart is passed in as the answer key; the model only explains. Server-side key, hard caps, and a checker that rejects invented numbers. First eval 8 of 15, after tightening 14 of 15.
Progress you cannot corrupt
XP, levels, badges and rating are derived from history, never stored. A 28-day simulated player proves they only move forward and streaks break and repair correctly.
Sync that survives bad networks
Progress merges on both sides. Pushes back off and retry, and a bad read on the phone writes nothing, so it can never wipe real progress.
A casino that is honest about itself
The engine decides every result and the table only animates it. Tourist Trap exists to let you feel what 6:5 costs. The highest-limit table is held back because it looks most like real gambling.
Privacy and safety designed in
Row-level security on every table, usage counters only the server can touch, no secret in the repo. The privacy policy's claims are tied to the code by tests.
How it got built
From a hunch to TestFlight.
1 · Engine and curriculum
Exact EV maths first, then 47 lessons written on top of it and tested against it.
2 · The app
Drills, a coach that names your mistakes, games, badges, streaks and reminders, all offline.
3 · The cloud
Accounts and sync on Supabase with row-level security, and an AI coach behind strict caps.
4 · Stability and compliance
A 28-day player simulation, sync robustness tests, US terms and privacy, a release gate.
5 · TestFlight
EAS builds, the beta, the App Store listing, and the rename to Upcard.
6 · The Cut, Ace and the redesign
A practice casino, Ace as a typed coach, a new Today, Learn and Profile, all shaped by tester feedback.
Screens
Fifteen screens from the current build.
Today
Learn
A lesson hand
Chart drill
The Cut
At The Parlor
Train
Ace
Profile
Levels and rating
Badges
Cheat sheet
The chart
Trip Prep
Trip planner
Scroll sideways · 15 screens
Why I built it
I got interested in blackjack the way a lot of people do — I sat down at a table, played on instinct, and lost. What bothered me wasn't the money. It was finding out afterwards that there had been a right answer the whole time — and I simply hadn't known it.
Basic strategy isn't folklore. It was solved with computer simulation decades ago, and it's a finite, learnable thing — roughly 340 decisions with a right answer each. But almost everything built around it is either a casino game wearing a teacher's costume, or a static chart you're told to memorise with no way to check whether you actually have.
So I built the thing I wanted: short lessons, drills that grade you and explain why, a simulator that deals a real shoe, and a mastery system that refuses to tell you you've got it until you've proved it under pressure. And — because this is the part the category gets wrong — a set of numbers that are honest about what all that is worth, including when the honest answer is "you're still losing money, just more slowly."
It's a personal project, built in the open on evenings and weekends, and it's in TestFlight beta right now.
But the real reason it exists is smaller, and more stubborn, than any feature. You never control the cards. In the end a hand comes down to luck, and no chart or drill will ever change that. What you can control is whether you played it right — and once you've genuinely learned this game, a loss stops feeling like a failure. It's just variance doing its job while you did yours. The app can't make the deck fall your way; it can only make sure that when it doesn't, the mistake was never yours — that you did everything the odds allowed, and let the rest be the rest. That's the whole promise. Not that you'll win, but that you'll never again lose to your own ignorance — and that, it turns out, is the only part of the game that was ever yours to win. If that sounds worth having, I'd like to hear from you.
♠
Shreyansh Ojha
Building Upcard
Straight answers
The questions people actually ask.
Is this gambling?
No. There is no real money anywhere in the app, in either direction. Nothing is deposited, wagered, won or withdrawn, and there is nothing to buy. Chips and dollar figures are practice numbers with no value, the way a flight simulator has an altimeter without leaving the ground.
Will it make me money?
No, and anything that says otherwise is selling something. Perfect basic strategy cuts the house's edge to about half a percent at fair rules. You still lose, just slowly. Only correct card counting can move the edge to the player, and that edge is thin, needs real capital and near-flawless play, and shows only over tens of thousands of hands.
What Upcard offers: you'll understand this game better than almost anyone at the table, and know exactly what that is and isn't worth.
What does the AI actually do?
It explains. It never decides. The right play always comes from the app's maths, and the full chart is passed to the model as the answer key. Ace can rephrase a mistake, give you a memory trick, or answer a typed question about your own play. Every AI reply is labelled, capped at a few a day, and the app works fully without it.
Is card counting legal?
Counting in your head is legal in most places. Casinos are private businesses and can ask a counter to leave. Using any device at a live table, including a phone or this app, is a crime in Nevada, New Jersey and many other jurisdictions.
The app is blunt about this. Upcard is for practice away from the table, nowhere else.
Do I need to be good at maths?
No. Basic strategy is something you learn, not something you calculate. Every lesson can be read in simplified language, and you can master basic strategy without anything harder than adding to 21. The maths is there if you want it.
What does "mastered" mean?
Four checks, all at once: 1,000 decisions, 97% right over your last 200, an average decision under 5 seconds, and practice on at least 3 different days. It recomputes every time, so a bad stretch pulls it back. The bar is always on screen.
Do I need an account?
No. Guests get the first two tiers of the course, The Parlor table, Quick Bite, 21 Rush, Trip Prep and the trip log. A free account unlocks everything else and syncs your progress across devices.
Is this the same app as "Blackjack Mastery"?
Yes. Same project, new name and icon.
What does it cost?
It's free in TestFlight beta, with no purchases and no ads. Join on TestFlight, or email me if the link says it's full.
TestFlight beta
Stop guessing. Start knowing.
Ten minutes on your iPhone: your first hand, a lesson, a few drills. Tell me what's confusing or broken. Free, no account needed.
For adults 18+, available in the United States only.
♠ Upcard — formerly "Blackjack Mastery." A practice simulator and training app.
No real money is ever wagered, deposited, or withdrawn in this app. Every dollar figure in it is a simulated training number with no value, and nothing here promises you winnings. Success in the app does not guarantee success in real-money games.
Card counting is legal to learn. Using any device to assist you at a live table is a separate matter and is a crime in Nevada, New Jersey and many other jurisdictions. This app is for practice away from the table.
Intended for an adult audience, 18+, available in the United States only. If gambling stops being fun, help is available — ncpgambling.org or 1-800-GAMBLER in the US, BeGambleAware.org in the UK.
© 2026 Shreyansh Ojha. All rights reserved.