An entry's name opens its live demo. Sizes are the plain files you copy, before minifying. Module docs list limits and the closest existing open-source project.
Modules & Tools (49)
Small pieces for single-file games and apps, and the tools that build and test them. Tools are not shipped inside a game.
Device and browser adaptation
Make a game behave on slow phones, privacy-focused browsers and power-saving screens.
- env-probes 1.1.0 · API 1: Detects privacy modes that round timers (including Firefox's 16.67 ms clock), scramble canvas read-back or block storage, and says what it found in plain words. global
EnvProbes· 16.2 KB · docs - frame-kit 1.2.1 · API 1: Frame pacing for canvas games: even-dt smooths the frame time, quality-governor steps effects down and back up, job-pump spreads heavy jobs across frames, frame-meter shows frames a second, hitches and tap delay in plain words. global
EvenDt,QualityGovernor,JobPump,FrameMeter· 38.9 KB · docs - field-report 1.0.2 · API 1: Two hidden buttons for a game or app: five taps in a corner open a panel that saves a speed report (start-up, frames a second, slowest frames, heavy tasks, plain verdict) and an error log, as small Markdown files. No network. global
FieldReport· 21.3 KB · docs - fx-governor 1.1.1 · API 1: Steps visual effects down when the device cannot keep up; never back up behind the player. global
FxGovernor· 6.2 KB · docs - image-decode 1.2.2 · API 1: Loads PNG, JPEG, WebP and AVIF pictures so the page does not freeze when they are first drawn: picks the right off-thread way for each browser, loads a list in order, and tells whether the browser can read WebP or AVIF. global
ImageDecode· 22.0 KB · docs - slow-note 1.0.0 · API 1: Keeps a short note, only on the device, of the errors, slow taps and long frames a page had; copyable as plain text, nothing is sent anywhere. global
SlowNote· 9.7 KB · docs
Saving and data safety
Keep a player's progress safe and let them move it between devices.
- save-kit 1.2.2 · API 1: Safe localStorage saves, backup slot, checksummed copy-paste save codes with a size limit on what a paste may unpack to. global
SaveKit· 26.6 KB · docs - tab-guard 1.1.1 · API 1: Keeps one open copy of a page in charge (Web Locks), so two tabs do not overwrite each other's saved data, and tells the game when the other copy closes. global
TabGuard· 9.6 KB · docs
Games - Looks and effects
Curtains, flying elements, lettering and 3D-looking sprites.
- cartoon-3d-kit 1.3.0 · API 1: A written style guide plus demo for the soft, glossy cartoon 3D look done in plain CSS and SVG. no script, a style guide · docs
- fly-to-mini 1.2.0 · API 1: A big element scrolls away and a copy flies to its sticky mini version (and back). global
FlyToMini· 18.1 KB · docs - gpu-blur 1.0.0 · API 1: Blurs a picture (a canvas, an ImageBitmap or RGBA bytes) on the graphics card with WebGL 2, or in WebAssembly, or in plain JavaScript, whichever the device does best; every way gives the same picture, and a big blur never freezes the page. global
GpuBlur· 37.4 KB · docs - sprite-baker 1.7.1 · API 1: Tiny software 3D rasterizer that bakes shaded sprites to canvases once at load, or one frame per tick; also makes silhouette masks and packs sprite sheets. Optional WebAssembly fill add-on (same pixels, about 1.1 to 1.4 times faster baking in Chromium and Firefox). global
SpriteBaker· 54.6 KB · docs - stage-curtains 1.4.0 · API 1: Velvet stage curtains that slide shut over a page, then fly open; the velvet is painted by a small WebAssembly loop with plain JavaScript as the fallback. global
StageCurtains· 46.2 KB · docs - sticker-text 1.1.0 · API 1: Die-cut sticker lettering in plain CSS text-shadow rings, no images. global
StickerText· 5.0 KB · docs
Games - Controls
Let players hold a button, or play with a gamepad.
- back-close 1.2.0 · API 1: Makes the phone back swipe or back button close the top panel instead of leaving the page (CloseWatcher, with an opt-in history fallback for browsers without it). global
BackClose· 9.1 KB · docs - hold-press 1.1.0 · API 1: Hold-to-repeat for buttons that survives Android Chrome pointercancel. global
HoldPress· 13.0 KB · docs - wake-keeper 1.1.0 · API 1: Keeps the screen awake only while a game wants it: released on pause, hidden tab and idle, asked again when allowed, no retry storms. global
WakeKeeper· 8.2 KB · docs
Games - Assist
Show a new player around, and keep small children away from the buttons that matter.
- grown-ups-door 1.0.0 · API 1: A hold-then-drag task a young child will not finish, in front of the buttons and links a grown-up should press (a speed bump, not security). global
GrownUpsDoor· 14.8 KB · docs - spotlight-tour 1.1.1 · API 1: A first-time tour: one dimmed layer, a bright window over the current part, Skip and Back, remembers who saw it and gives a finishing gift once. global
SpotlightTour· 12.8 KB · docs
Games - Math
The numbers behind idle and clicker games.
- graph-walk 0.1.0 · API 0: Breadth-first distances and depth-first loop marking over a links-of-every-item layout in typed arrays, with no recursion. Same answers as Netflow Map's inline walks. global
GraphWalk· 4.0 KB · docs - idle-core 1.2.0 · API 1: Tested maths for idle/clicker games: costs, buy-many and buy-max, milestones, away income, boost queue, number format. global
IdleCore· 22.8 KB · docs
Games - Testing
Test a game by playing it at random, shrinking any failure to a short replay, counting what it draws and driving real browsers.
- canvas-probe 1.1.1 · API 1: Test-build counter for canvas 2D games: calls per frame, save/restore leaks, overhanging drawImage sources, draws below half size, style-write repeats, painted area.
- firefox-stand-in 1.1.0 · API 1: Runs a Playwright-for-Python test in stock Firefox (through Selenium and geckodriver) without rewriting it; says plainly which calls it supports and stops with a clear message on the rest.
- fuzz-kit 1.3.4 · API 1: Seeded, reproducible random-input fuzzer engine with weighted operations, invariants, liveness checks and failure shrinking; Playwright and Puppeteer runners with real input and CPU throttling; stock-Firefox recipe; test-hook stripper.
- speed-guard 1.0.0 · API 1: One command that says whether a release got slower than the one before it, from the speed-history files, and which browser checks a change needs re-run. It runs nothing itself, so it costs no browser time.
- speed-lab 1.1.1 · API 1: One-button speed test run on the device: compares your page with parts switched off, keeps the scene in view and uncovered, and says the answer in plain sentences with a copyable table.
- storage-probe 1.1.0 · API 1: Page that tells you in plain words whether copies of a page saved in different folders share their saved data, see each other's writes and locks; one button, copyable report.
- test-isolation 1.1.0 · API 1: Puts a prefix in front of every localStorage key on a test page, so a speed test or random-play run never touches the real saved game.
- test-runner 1.3.0 · API 1: Shared pieces for browser checks and speed tests: warm browsers, a four-browser runner, fair timing, skip-unchanged wasm builds, a wasm-versus-JavaScript twin test, a picture fingerprint gate and an automatic bisect.
- webkit-driver 1.4.1 · API 1: Drives WebKitGTK or GNOME Web from Node with no dependencies, using the call names of Playwright and Puppeteer (goto, evaluate, waitForFunction, mouse, keyboard, screenshot, console errors), so a test written for them can also run in WebKit.
App - Efficiency
Keep a one-file app small and light: smaller data in memory, smaller pages on the wire.
- elias-fano 1.4.0 · API 1: Keeps sorted whole numbers (ids, positions, links of every item of a map) in a third to a half of the memory of plain arrays and still answers 'value number i' and 'first value at or above x' without unpacking; also keeps many sorted lists in one structure and decodes them all at once. WebAssembly with SIMD, plain JavaScript fallback with the same answers. global
EliasFano· 62.3 KB · docs - lfc-pack 0.1.9 · API 0: Packs newline-delimited JSON (logs, events, API dumps) into LFC-pack (.json.lfc): every field becomes a typed column inside zstd blocks, with a footer of per-block number ranges. Reads back the same rows as JSON.parse (or the exact original bytes), only some keys, or only a time range, with helper workers for big files. WebAssembly is required; a Python reader is included. global
LfcPack· 697.5 KB · docs - memory-compression 2.6.5 · API 2: Keeps big data packed in memory and brings it back exactly, in one file with one pack/unpack: bytes and typed arrays (a 120 MB scene shrinks to 52%, 41% in small mode, and restores in about 239 ms in Firefox 158.0, against 312 ms with lz4-wasm and 1.5 s with fflate; lower is better) and big lists of plain JavaScript objects (300,000 link objects shrink to 14% of their JSON text, 35% for msgpackr with records). Picks the right layer by itself; MemoryCompressionJSO stays as an alias. global
MemoryCompression· 395.7 KB · docs - single-file-tools 1.2.0 · API 1: Font subsetting, safe inline-SVG tightening and a Zopfli self-extracting packer for one-file games.
- text-columns 0.1.1 · API 0: Reads CSV or TSV text into typed columns: plain decimal columns come out as Float64Array straight from the bytes, the rest as text. The field scan runs in WebAssembly SIMD; plain JavaScript gives the same answers. global
TextColumns· 17.4 KB · docs
Model simulation
Simulate random walkers over a graph.
- walker-sim 2.4.0 · API 2: Simulates random walkers on a network with seeded, repeatable runs, 16 random-number distributions, 95% ranges and the exact odds to check against (1,000,000 walkers in about 52 ms with the WebAssembly loop in Chromium 155 and Firefox 158, lower is better). Big runs use a WebAssembly loop first, JavaScript when it cannot. global
WalkerSim· 73.4 KB · docs
Visualization
Draw maps, flow charts and animated pictures from data.
- gif-writer 1.5.1 · API 1: Writes animated GIFs from canvas pictures with one shared palette, storing only the pixels that changed (about 6.8 times smaller than gifenc on a mostly still animation). global
GifWriter· 44.0 KB · docs - clip-writer 1.0.1 · API 1: Turns pictures into a short MP4 or WebM video in the browser with the browser's own video encoder and two small file writers, no libraries; the same add/finish shape as gif-writer, and about 8 times smaller than a GIF of the same pictures in Netflow Map. global
ClipWriter· 11.4 KB · docs - netflow-engine 2.2.2 · API 2: The engine of Netflow Map as a module you can copy and adapt: nine views of a map and eleven network layouts, no two items on top of each other, WebAssembly twins for Force and Distances, and a use() hand-over for the layers and Sankey add-ons; a 30,000-item network lays out in about 0.8 s in the Netflow Map app (Firefox). global
NetflowEngine· 205.2 KB · docs - netflow-layers 1.5.1 · API 1: Lays out a graph in rows (top to bottom or left to right) with story order, tags instead of very long links, a column for the pages every route passes, and tall maps cut into columns. global
NetflowLayers· 50.9 KB · docs - netflow-scene 1.3.1 · API 1: Turns a Netflow Map layout into plain drawing lists (dots, links, labels, ribbons, shapes) that Canvas 2D, WebGL2, WebGPU or SVG can draw the same way; big flat maps keep links in typed lists and reuse link looks between pictures. global
NetflowScene· 114.7 KB · docs - netflow-sankey 2.3.0 · API 2: Lays out a flow chart (Sankey) from a plain list of links, with about half the weighted crossings of d3-sankey on the charts measured, backward links drawn instead of crashing, and an SVG drawer. global
NetflowSankey· 48.2 KB · docs
Size and packaging
Open zip and Excel files safely, and pack a finished page into a smaller file that unpacks itself.
- lzma-decode 1.3.0 · API 1: LZMA1 decoder that uses WebAssembly first (about 1.5 to 2.6 times faster to open a page) and falls back to a small readable ES5 JavaScript decoder; tested against Python's lzma. Browsers can only unpack gzip and deflate natively. global
lzmaDecode· 22.2 KB · docs - lzma-pack 2.0.0 · API 2: Packs one HTML file into a smaller self-unpacking file with LZMA and a hash check (Python 3 standard library).
- pcodec-js 1.6.1 · API 1: Pcodec for web pages: unpacks (and optionally packs) big lists of numbers in a browser, one file, same bytes as any other Pcodec. The unpack-only file is 61 KB gzipped (the other JavaScript build of Pcodec is 324 KB), streams a 4,000,000-number file in 6.3 MB of memory, and WebAssembly is required (no plain-JavaScript backup). global
PcodecJS· 104.0 KB · docs - ppmd-decode 1.3.0 · API 1: A PPMd (7-Zip PPMd7) decoder that uses WebAssembly first (about 1.4 to 1.8 times faster to open a page) and falls back to one ES5 JavaScript function, about 6.6 KB packed. It unpacks web-page data about 10% smaller than LZMA, but slower. PPMd is by Dmitry Shkarin; the public-domain code it follows is Igor Pavlov's, from 7-Zip. global
ppmd7Decode· 45.3 KB · docs - ppmd-pack 2.0.0 · API 2: Packs one HTML file into a self-unpacking file with PPMd, the 7-Zip text compressor (PPMd by Dmitry Shkarin; public-domain code by Igor Pavlov, 7-Zip). Pure Python; pays off above about 60 KB of compressed data.
- zip-open 1.3.1 · API 1: Opens .zip and Excel .xlsx files safely: limits counted on what really unpacks, so a zip bomb stops at the limit with a plain-words note. global
ZipOpen· 32.5 KB · docs
Story editor packages (10)
Packages for interactive stories, kept with the Story Editor they are cut from (source). Each is MIT-licensed, has no dependencies, and runs in Node 18+ or a browser.
Story data
Create, clean, import and save stories in one shared file format.
- story-diff: Says in plain words what one edit did to a story, such as "Add page “The Cellar”".
- story-format: Create, clean, search, import and export interactive stories as JSON, with a JSON Schema. Twine import lives in twine-import.
- story-outline: Turns an indented outline into pages and choices, or into a whole branching story.
- twine-import: Reads Twine stories (Twine 2 HTML, Twee 3, Twine 1) and turns SugarCube and Harlowe code into rules, with a plain-words report.
Story validation
Find dead ends and endings nobody can reach before a reader does.
- story-check: Exact checker for branching stories with items, numbers and dice: dead ends and endings no player can reach.
Story flow
See a story's shape: maps of its pages and simulated readers.
- story-map: Layered, arc and matrix drawings of a story graph (SVG) and seeded simulated players.
Story build and distribute
Turn a story into a game, or play it from code or a terminal.
- story-player: Build one offline HTML game from a story, or play a story from code or a terminal.
Story packaging
Pack a finished story page into a smaller page.
- zip-page: Wrap a finished HTML page into a smaller page that unzips itself, with a pure-JS inflater fallback.
Story testing
Run tests on stock Firefox, generate random stories and keep two implementations in step.
- contract-kit: A guide and a helper (about 7.2 KB minified) for keeping two implementations of one rule set from drifting apart: seeded random inputs, a side-by-side comparison (also for async functions), shrinking a failing input to a small one, a field table and a time limit; runs in browsers too.
- qa-kit: Tiered test runner and a Playwright-style API over WebDriver BiDi for stock Firefox; seeded random-story generator.
AI knowledge base (1)
Written processes for working with an AI helper, kept with the Story Editor.
Working with an AI helper
A written process for a person and an AI assistant building software together.
- ai-collab-kit: A written process and templates for a person and an AI assistant building software together.