PartyGrids

How the cards and puzzles are made

A plain-language description of what the generators on this site do with your word list, what they guarantee, and where the limits are.

The short version

The cards and puzzles are generated in your browser. A bingo game or a word search is described by your inputs plus one number, the seed, and the same inputs and seed always produce exactly the same cards or grid. That is what makes the share link work: it carries the inputs and the seed, so any device can rebuild the game, and it is why the printed caller sheet, the on-screen caller and the cards always agree.

Randomness and seeds

The generators never call the browser's built-in random number function. They use a small, well-known pseudo-random generator (mulberry32) started from the seed, so a sequence of "random" choices is reproducible. The only unseeded choice on the site is the fresh seed picked when you press Shuffle: that gives you a new game, and reopening a link gives you the old one. The seed is an ordinary integer stored in the link along with your list and settings.

Bingo cards

Your list is cleaned first: items are trimmed, blank lines dropped, and duplicates removed without regard to case, keeping the first spelling. Then, for each card:

  1. Items are dealt from a bag: a seeded shuffle (Fisher–Yates) of the whole list, refilled with a fresh shuffle when it runs out. The card takes 24 items (or 25, 16, 9 or 8, depending on the grid and the free space), so across a game every item is used about equally often and no item is left off a class set. The free square sits in the centre of 5 x 5 and 3 x 3 cards when it is on.
  2. If the card's set of items repeats an earlier card's, one item is traded, with the bag when that keeps the counts even, otherwise with an earlier card, until the set is new. If no trade works after many tries, the game is still made and a warning suggests another seed; the automated tests check that this does not happen on any themed list, on tight lists built to force trades, or on hundreds of random jobs.
  3. The items are then shuffled across the cells until the arrangement differs from every earlier card. If random shuffles keep colliding, the arrangements are walked in order, so a repeat is impossible while any arrangement is left.

The result reports two flags. Distinct cards is always true when cards were made: no two cards share an arrangement. Distinct sets is true when no two cards share a set, which the engine achieves whenever the number of possible sets, C(n, k), is at least the number of cards you asked for; when C(n, k) is smaller, the game is still made and a warning says so. A second, milder warning appears when the list has fewer than twice the squares on a card, because such cards share most of their items. The unique cards guide has the table.

The caller sheet is every usable item in the list, shuffled once with the same seeded generator. Because cards are dealt evenly, every item lands on a card once the game has enough cards for the list (roughly cards times squares per card at least the number of items); in a smaller game some calls match no card, which is how number bingo works too. The engine also handles classic column bingo, where each column draws from its own range (B 1 to 15 through O 61 to 75), with the same evenness per column; the themed pages are all free-choice word lists.

Word searches

Each word is upper-cased and reduced to its letters (any script), so "ice cream" is placed as ICECREAM while the word bank keeps your spelling. Words are placed longest first, each at a seeded-random position and allowed direction, with or without crossing other words at matching letters depending on your setting. When a word finds no free slot, the engine tries every slot, then tries moving up to two placed words out of the way; a word that still cannot be placed is reported with a reason: too long for the grid, a single letter, a duplicate of another word, or no room.

Empty cells are then filled with letters, A to Z by default, or the distinct letters of your words if any word uses a letter outside A to Z, drawn with weights that favour the letters your words use so that rare letters do not give a word away. After filling, the whole grid is scanned in all eight directions for every placed word. If any word occurs more than once, the filler letters responsible are re-rolled and the scan repeats, up to a fixed number of rounds. The result's single occurrence flag is true when every placed word appears exactly once. The cases the generator cannot fix are a word contained in another (CAT in CATTLE) and a word that is another spelled backwards (STAR and RATS); it warns you about both so you can change the list. Two rarer cases are also reported: a word that other words' letters happen to spell a second time is moved to another slot, or dropped and listed as not fitting when it cannot be moved; and a fill alphabet so small (a letter or two) that the re-rolls run out leaves a warning that some words can still be found more than once.

Limits

  • Up to 200 cards per bingo game and up to 500 items in a bingo list.
  • Up to 60 words in a word search, on a grid from 5 x 5 to 40 x 40.
  • The share link holds the whole game, so very long lists make long links. Browsers and chat apps handle links of several thousand characters, but a list of hundreds of long phrases can be awkward to paste; the PDF is the better way to hand such a game to someone else.
  • The generators are deterministic, so a change to how they work could make an old link produce different cards. Changes like that are listed in the changelog; keep the PDF of any game you need to reproduce exactly.

The PDF

PDFs are built in your browser with the pdf-lib library and two of the standard PDF fonts (Helvetica and Helvetica Bold), which are built into every PDF reader and keep files small. Those fonts cover the WinAnsi character set: the Latin alphabet with the accents used in Western European languages, digits and common punctuation and symbols. Emoji, Cyrillic, Greek, Arabic, CJK and most other scripts cannot be printed with them, so the tool checks every item before you download and tells you which ones won't print. Those items still work on screen and in the share link.

Cards are laid out 1, 2 or 4 per page on Letter or A4, with the title above each card, optional header letters above the columns, an optional "Card 3 of 30" label, a small footer line with the site address, and the caller sheet appended as its own pages. Very long phrases become small on a 4-per-page card; check the preview before you print a class set. Word searches print one grid per page with the alphabetical word bank underneath (or on a page of its own when a large grid leaves no room) and, if requested, an answer key page with the placed words highlighted. The Print button is an alternative that uses the browser's own fonts, so it can print text the PDF fonts cannot.

Word ideas from a theme

The word-ideas box, on the bingo and word search makers and on the AI bingo card generator, is the one part of the site that doesn't run in your browser. It sends the theme you type, and nothing else, to the site's server, where a language model is asked for a list on that theme: about twice as many bingo squares as a card holds, single words for a word search, or answers with clues for a crossword. On the crossword maker it can also write clues for answers you typed without one; then only those answers (up to 40 at a time) and the theme, if there is one, are sent, and clues you wrote yourself are never replaced. The model is told to keep the list family-friendly, specific to the theme and free of filler.

Whatever comes back is checked before you see it. Bingo squares longer than 28characters or 5 words are dropped, because they don't fit a square. Word search words must be single words of 3 to 12 letters. Numbering, stray quotes, emoji and repeats (including the same word in different capitals) are removed, and both the theme and every suggestion are screened against a list of words that don't belong in a family game. Crossword answers must be 3 to 15 letters in at most3 words, clues are capped at 100 characters, and a clue that contains its own answer is rejected. If too few usable suggestions are left, you get a message instead of a short list. Clues are a draft like everything else from the box: check facts before you print.

Unlike the card generator, the ideas are not seeded: asking twice gives different suggestions. They are a starting point to read and edit. Once you use them they become ordinary items in your word list, so everything above (the uniqueness guarantee, the share link, the caller sheet) applies to them exactly as it does to words you typed yourself.

Crosswords

The crossword maker builds a free-form classroom crossword from your answers: words interlock in a compact grid rather than filling a dense newspaper square. Each answer is reduced to its letters (spaces, hyphens and apostrophes are dropped, accents are kept), and a phrase can show its word lengths after the clue, such as (5,3). Up to 60 answers of 2 to30 letters fit in a grid of at most 30 x 30.

The generator tries hundreds of seeded arrangements and keeps the one that places the most answers, then has the most crossings, then fills its grid best and is closest to square. Every arrangement follows the same rules: each answer reads exactly once in its direction with an empty square before and after it, letters touch only where two answers cross, so every run of letters in the grid is one of your answers, and all the answers form one connected puzzle. Squares are numbered in reading order wherever an Across or Down answer starts. An answer that can't join the puzzle (because it shares no letters with the others, or there is no room) is listed with the reason instead of being dropped quietly. As with the other tools, the seed is in the share link, so the same list always rebuilds the same puzzle.

The PDF shrinks the grid before it lets the clues run onto a second page, prints Across and Down side by side when they fit, and puts the answer key on a page of its own with the grid in the same place, so you can hold the two up to the light to check.

What is stored, and where

Your most recent game is kept in this browser's local storage so it is there when you come back on the same device, and the caller keeps the number of calls made for each game the same way. A number game started on the caller page keeps its seed and its place in the page address instead, so a reload or a shared link carries on with the same order. Your word lists and games are never sent to a server, and the site has no database of games; a theme typed in the word-ideas box is used to write the suggestions and not kept. The share link is the only portable copy, and anyone with it can see the list. The privacy policy has the rest.

How the engine is tested

The generators have automated tests that check the guarantees described above: that no two cards in a game share an arrangement, that sets are distinct whenever the list allows it and a warning is given when it doesn't, that items are spread evenly across a game, that the caller sheet contains every usable item exactly once, that every placed word occurs exactly once in a word search, that words which cannot be placed are reported with the right reason, and that the same inputs and seed always produce the same result. A further test runs every themed list through the engines, so each landing page opens with a complete, warning-free game.

Accuracy and corrections

The counting in the guides is calculated by code when the pages are built, not typed in, and the engine's behaviour is checked by the tests described above. If you find an error, please report it; corrections are listed in the changelog.