Online Card Shuffler

How to play

1. How do you shuffle a deck of cards online?: The page opens on a deck that is already shuffled, so there is nothing to configure. Press the Shuffle button at the bottom for a fresh one: the deck splits into two halves, riffles back together and settles into a single stack, and the seed code above it changes to a new string. Everything runs in your browser — no request is sent anywhere.
2. How do you draw cards after shuffling?: Tap the deck itself to draw one card, or use the Draw 1 and Draw 5 buttons underneath. The card slides off the top and flips over; the newest one sits in the large slot beside the deck and older ones line up in the grid below, newest first. The counter drops and the stack visibly gets thinner — this is a finite deck, not an independent random draw.
3. How do you give someone the exact same shuffle?: Press Copy deck link next to the seed code and send the link — opening it produces a card-for-card identical deck. You can also just read the code out loud (it looks like 1N-k3f9a2) and let them type it into Open a deck from a seed code at the bottom of the Deck settings drawer. The code is a recipe, not a password: anyone holding it can see the whole order.
4. How do you shuffle multiple decks or add jokers?: Open Deck settings with the gear in the top-right corner. Decks goes from 1 to 8 and jokers can be switched on or off, so the biggest deck is 8 × 54 = 432 cards. Changing either one shuffles a fresh deck and issues a new seed code, because the old order means nothing under a different deck. The same drawer sets how many cards a draw takes and can skip animations.

Rules & variants

What this online card shuffler does: the page loads on a shuffled standard deck — one deck, 52 cards, no jokers by default. The big button at the bottom shuffles the whole deck and issues a new seed code. The deck itself is tappable and draws one card; the three preset buttons under it draw 1, draw 5 and cut. This is a finite deck: a card you have drawn will not come back until you reshuffle.

Which algorithm it uses: every shuffle is a standard Fisher–Yates shuffle — walk the deck from the last card backwards, swapping each card with a random earlier one. The shrinking swap range is what makes it uniform, unlike the popular trick of giving every card a random score and sorting on it, which in measured tests makes some orders come up more than twice as often as others.

Why there is only one shuffling method: simulating a real-world technique mostly simulates a badly shuffled deck. A riffle shuffle needs roughly 7 repetitions to get close to uniform (Bayer and Diaconis, 1992, using variation distance; Trefethen and others argue 6 may do under a different measure), while the overhand shuffle is dramatically slower — Pemantle's 1989 lower bound is at least 50 repetitions and computational work often lands in the thousands; Jonasson proved an O(N² log N) order in 2006. Offering an unshuffled-looking result as a peer option would just hand you the judgement call. So the result here is always uniform and the shuffling technique only drives the animation.

The two randomness modes and what each costs: reproducible mode (the default) starts from a 32-bit seed, so it can reach about 4.3 billion orders. That is plenty for a card game, a classroom or a demo, but it cannot cover every arrangement of a deck — 52 cards have roughly 8×10⁶⁷ orders and no 32-bit seed holds that. What you get in exchange is a short code that describes the deck completely, so somebody else can reproduce it card for card. Crypto mode draws from the browser's cryptographic random source and can reach every order, at the cost of being unreproducible — by anyone, you included, which the page states plainly. We do not claim "true randomness" anywhere.

How to read a seed code: a code looks like 1N-k3f9a2. Before the dash is the deck — a digit for how many decks (1 to 8) and a letter for jokers (N for none, J for jokers). After the dash is the seed itself, written in base 36, at most seven characters. The deck is baked into the code on purpose: the same seed produces completely different orders under one deck versus two decks with jokers, so a seed-only code would quietly lie to whoever received it. Retyping 1N-k3f9a2 as 2J-k3f9a2 gives you a different 108-card deck — that is the design working, not a bug.

Drawing, cutting and running out: drawing consumes no randomness at all — the order was fixed the moment the deck was shuffled, and a draw just takes the next cards off the top. If fewer cards remain than you asked for, you get what is left: with 8 cards remaining, Draw 10 hands you those 8 without padding or an error. Cutting rotates the remaining cards as a block — the top portion moves underneath, the count does not change by a single card, only the order does. The cut always lands between 20% and 80% of the remaining cards, because cutting off one card is not a cut. Below 4 cards the cut is refused with a visible reason. When the last card is gone the main button turns into Reshuffle and the full order opens up for checking.

The two views of the full order: once the deck is empty — or any time you expand the collapsed section — you can read the full order in two views. Draw order is the sequence in which you actually received the cards; Shuffle order is the deck the seed code stands for, and cutting never touches it. The two only agree if you never cut. To check whether two people hold the same deck, compare the shuffle order, because that is the only thing a seed code promises.

Which mode to use when: classroom demos, worked examples, test fixtures and sending a deck to a friend all want reproducible mode with the code attached. A game where nobody may know the order in advance wants crypto mode, accepting that the deck cannot be recovered afterwards. To verify two people hold the same deck, compare seed codes rather than reading out 52 cards. And if you want the physical deck in your hands genuinely shuffled, do not stop at two or three riffles — see the numbers above. This page makes no claim whatsoever about improving your odds or predicting the next card; it is an electronic deck, nothing more.

A full session, step by step: start on the default 52-card deck. Press Shuffle — the status line reads Shuffled, 52 / 52 left, and the seed code changes. Tap the deck for one card and the count drops to 51. Press Draw 5 and five cards flip out one at a time, leaving 46 with six cards in the grid. Press Cut: the count stays at 46 — proof that a cut changes the order and nothing else — but the next card you draw is no longer the one that was next before. Keep drawing until the count hits zero; the deck position bursts, a banner says all 52 were drawn, and the main button becomes Reshuffle. Throughout, drawn plus remaining is always exactly this deck: no card ever duplicates or disappears.

Checking a deck across two devices: A shuffles on a phone and gets 1N-k3f9a2, presses Copy deck link and sends it. B opens the link; the page builds that exact deck, shows 1N-k3f9a2 with 52 / 52 left, and clears the parameter out of the address bar so B's own refreshes keep B's progress instead of resetting. Both expand Shuffle order and compare — all 52 cards match, position by position. How many each has drawn or cut is their own business and does not affect the comparison.

Privacy and offline use: there is no account, no nickname and nothing to fill in. Shuffling, drawing, cutting and seed-code encoding all run inside your browser, so no result is ever uploaded. The deck state — remaining order, drawn order, cut count — is kept in your browser's local storage, so a refresh or a trip to another app brings the same deck back; the drawer has a Clear this site's data button. Once the page has been cached it keeps working offline. If local storage is blocked (private mode, quota full) everything still works — a refresh simply shuffles a new deck, and the drawer says so.

FAQ