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Enormous plain-text library explaining what every placement and aspect is supposed to mean, unpaywalled since the early 2000s.

A breathing bubble with adjustable pace, sitting on a page that mercifully does not require the app to work.

A collage assembled entirely from GeoCities pages — every GIF, marquee and tiled background salvaged and put back to work.

Type any web feature and see which browsers support it, version by version, alongside how many people actually use each one.

Two near-identical interfaces, one of them subtly wrong. Getting past the third level takes an unreasonable amount of care.

Opens as ASCII candy counting up on a blank page and quietly becomes a full role-playing game with a sea, a shop and a dragon.

Turns a snippet of code into a tidy image with your choice of theme, font and window frame. The tool behind a lot of shared code screenshots.

Thirty-odd card games with competent bots, no accounts and nothing covering the table. The default answer to fancying a game.

Cut-out cats rain down and bounce off the bottom of the screen, and you can grab one and fling it at the others.

A free endpoint that returns one cat fact per request, which is how every cat-facts prank bot ever built gets built.

Twenty years of forensic argument about how tall film stars really are, with photographic evidence and footwear analysis.

Estimated fortunes for anybody famous, sourced loosely, and impossible to stop clicking once you look up the first one.

The four-day jam game that grew into Celeste: thirty screens of very precise dashing, running in the page at PICO-8 resolution.

Anime avatar makers with genuinely good line art, including versions that output something usable as a profile picture.

Per-component checklists — buttons, forms, cards, empty states — covering the things everyone forgets until review.

A stocked chemistry bench in the browser where you can mix reagents and get it badly wrong at no cost.

Chess tactics training with a rating that goes down, plus an endgame trainer that reveals exactly how much you do not know.

Nearly a million recorded games from four centuries of chess, replayable move by move, with the real arguments in the comments.

A chihuahua rotating to a dance track, which was apparently a complete website idea in 2013 and somehow still is.

Long branching novels where your stats matter and the prose does not embarrass itself; a good number play free in the browser.

Community-written choose-your-path stories with ratings, which is the only thing keeping the good ones above the fan fiction.

Google's stripped-back sketchpad — pencil, pen, marker, chalk — with pressure support and absolutely no other features.

The offline dinosaur from Chrome's error page, playable while you still have a perfectly good connection.

Fourteen small experiments — spectrogram, harmonics, arpeggios — that explain how music works by letting you break it.

A history map with a timeline slider, layered with rulers, religions, battles and linked encyclopedia articles.

Scanned American newspapers from 1770 to 1963, full-text searchable, which is a dangerous thing to discover on a weeknight.

Five photographs, one question each: what year was this taken? Points scale with how close you land, and the cars always give it away.

How far you can get by train from any European station in five hours, drawn as coloured bands. Ruinous for an afternoon's productivity.

Parody religion with its own prophet, apocalypse date and merchandise, committed to the bit long enough that you stop being sure.

Open-city driving with traffic and no mission attached, for when you want to obey a speed limit in peace.

Video walks through a real city, and your job is to work out which one from the shopfronts, number plates and pedestrians.

Renders every road in any city as white lines on black and nothing else, which turns an ordinary street plan into unexpectedly good art.

Decades of adverts preserved exactly as broadcast, including the jingles you will regret having remembered.

Several thousand DOS, Amiga and console titles catalogued with screenshots, each playable without leaving the page.

Paint over the tourist, the bin or the power line and it fills in whatever should have been behind them.

Click monsters, hire heroes to click for you, then ascend for souls. The clicker that dragged the whole genre onto Steam.

Viral-content parody taken well past the point of sense, including quizzes that insult you for finishing them.

Sixty seconds to forge the Mona Lisa with a mouse, then a pixel-by-pixel score telling you exactly how badly it went.

A global membership devoted to looking up, with a cloud of the day and a manifesto against blue-sky thinking.

Curated stumble button that sends you somewhere good rather than somewhere random, with categories if you are feeling fussy.

The word-association board game in a free, well-built online room: two spymasters, one grid of code names, nothing to install.

A browser playground for HTML, CSS and JavaScript, plus an endless stream of other people's demos to open, read and remix.

Run a coffee stand for fourteen days, adjusting recipe and price daily, and learn more about margins than from any lecture.

The murmur of a café without the queue or the cost, built on research that moderate background noise helps creative work.

A plain, ad-free bank of cognitive tests — n-back, digit span, Stroop, mental rotation — that keeps a history of your scores.

Settlers of Catan in a browser tab, complete with the trade negotiations and the one player who will not give you wheat.

Match hue, saturation and complementary colours against a target, one exercise at a time, scored out of a hundred.

Hand-picked four-colour palettes posted daily and sorted by mood, with none of a generator's randomness.