# ExplainerTools

> A library of interactive explainers. ExplainerTools makes its own interactive models (Originals) and lists independent creators’ explainers with credit and a link to the original work. See it. Change it. Understand it.

Every listing names its creator. Originals label each simplification with a “Model ·” tag and keep their equations, assumptions and sources in the model notes on their tool page. This file is a convenience map of the public catalog. It is not a ranking or indexing promise, and it links no account, request or subscriber data.

## Read the catalog as data
- [Guide for agents and developers](https://explainertools.com/agents/): what each resource contains, its limits and how to credit creators
- [Catalog index (JSON)](https://explainertools.com/agents/catalog.json): 288 explainers and 90 creators with canonical, source and resource URLs
- [Creators index (JSON)](https://explainertools.com/agents/creators.json): every credited creator
- Explainer records: `https://explainertools.com/agents/explainers/{id}.json`
- Creator records: `https://explainertools.com/agents/creators/{id}.json`
- Read-only MCP endpoint: `https://explainertools.com/api/mcp/` (JSON-RPC over HTTP POST; tools search_explainers, get_explainer, get_creator)

## Topic guides
- [How could suction and thrusters help a car grip and launch?](https://explainertools.com/topics/tesla-roadster/)
- [Why can the Hunter’s Moon look orange as it rises?](https://explainertools.com/topics/hunters-moon/)
- [Why does Starlink have less lag than older satellite internet?](https://explainertools.com/topics/starlink/)

## Subjects
- [Math explainers](https://explainertools.com/subjects/math/): 38 in the collection
- [Science explainers](https://explainertools.com/subjects/science/): 113 in the collection
- [Computer Science explainers](https://explainertools.com/subjects/computer-science/): 65 in the collection
- [Engineering explainers](https://explainertools.com/subjects/engineering/): 54 in the collection
- [Society explainers](https://explainertools.com/subjects/society/): 15 in the collection
- [Design explainers](https://explainertools.com/subjects/design/): 3 in the collection

## ExplainerTools Originals
- [How does a folding phone close flat without folding its screen flat?](https://explainertools.com/originals/teardrop-hinge/): Close a folding phone with three different hinges and watch the screen's tightest bend, its glass strain and the gap between the halves.
- [How does a folding phone's glass screen bend without breaking?](https://explainertools.com/originals/folding-screen/): Change the fold radius, glass thickness and whether the layers are glued or sliding, and watch the glass strain cross the break line.
- [How do a few turns become one direction?](https://explainertools.com/originals/flocking-local-rules/): Change only the strength of local heading alignment while speed, neighborhood, noise and seed stay fixed; follow the directional-order readout without treating it as flock tightness.
- [Why does the ground stay warm?](https://explainertools.com/originals/greenhouse-balance/): Adjust one ideal gray layer’s effective infrared absorption and follow the conserved fluxes and equilibrium temperatures while sunlight and albedo stay fixed.
- [Does a prism create a rainbow?](https://explainertools.com/originals/prism-lab/): Change hypothetical dispersion while prism geometry and the incoming ray stay fixed; the sampled colors converge to one still-bent beam.
- [Why does oxygen let go?](https://explainertools.com/originals/hemoglobin-handoff/): Change oxygen partial pressure and watch modeled hemoglobin saturation move along a cooperative Hill curve from a lung-side reference toward mixed-venous pressure.
- [How much can compound interest really grow?](https://explainertools.com/originals/compound-growth/): Change return and starting age to see years invested through a fixed ending age of 80, doubling time and the cost of starting ten years later.
- [Can small cars in a tunnel move as many people as buses?](https://explainertools.com/originals/loop-lab/): Change car headway, riders and loading bays to see whether the tunnel or station limits people per hour.
- [Why are the northern lights green?](https://explainertools.com/originals/aurora-chamber/): Raise incoming electrons’ energy and watch the curtain reach lower, from high red oxygen through green oxygen to a nitrogen fringe.
- [Why doesn't a compass point to the North Pole?](https://explainertools.com/originals/compass-field/): Pick a city and year to see true north separate from magnetic north in an explicitly simplified field model.
- [Why is a rainbow always a circle?](https://explainertools.com/originals/rainbow-lab/): Move the Sun and see why drops on a 42-degree cone form a circle around the shadow of your head.
- [Why do some buildings fall in earthquakes while others stand?](https://explainertools.com/originals/quake-tower/): Change floor count and see a tower’s natural period move into and out of resonance with two-second ground motion.
- [How does a maglev train float?](https://explainertools.com/originals/maglev-lab/): Change train speed and watch induced currents build enough lift to clear the guideway while a travelling magnetic wave matches the train.
- [How does an AI chatbot pick its next word?](https://explainertools.com/originals/next-word/): Move temperature and a deterministic sample point to see illustrative next-token logits become narrow or surprising probabilities.
- [Why do walking robots fall over so easily?](https://explainertools.com/originals/balance-lab/): Push a code-drawn humanoid and move its next step to see how the capture point shifts and why a short step topples it.
- [Why does twice the speed need four times the braking distance?](https://explainertools.com/originals/stopping-distance/): Change speed, reaction time and braking grip to separate the distance traveled before braking from the distance needed to stop.
- [When should a falling rocket light its engine?](https://explainertools.com/originals/landing-burn/): Move a booster's ignition height and see why too early climbs again, too late hits, and one modeled height reaches zero speed at the pad.
- [Why do you mostly see satellites just after sunset?](https://explainertools.com/originals/satellite-dusk/): Move the Sun below your horizon and watch Earth's shadow rise through low orbit until a 500-kilometer satellite goes dark.
- [How high can you count on ten fingers?](https://explainertools.com/originals/binary-fingers/): Raise code-drawn fingers worth 1 through 512 and see ten binary switches represent every number from 0 to 1,023.
- [Why is a low gear easier on a hill?](https://explainertools.com/originals/gear-lab/): Choose a chainring and rear cog, then watch one pedal turn trade wheel speed for the force needed at your foot.
- [Why does the Moon change shape?](https://explainertools.com/originals/moon-phases/): Move the Moon around Earth and watch the visible lit fraction change while sunlight always illuminates one lunar half.
- [Why does airplane mode matter?](https://explainertools.com/originals/airplane-mode/): Drag a phone up to cruising altitude and watch its radio climb to full power as the towers it can reach fall out of range.
- [How does GPS know where you are?](https://explainertools.com/originals/gps-lab/): Drag satellites into view and watch their timed signals shrink your phone's position to a single point.
- [Why do LED lights flicker on camera?](https://explainertools.com/originals/led-flicker/): Drag a phone camera's shutter speed and watch the dark bands from pulsing LED light disappear when each exposure spans one whole pulse.
- [Why does Wi-Fi slow down through walls?](https://explainertools.com/originals/wifi-walls/): Add walls between a router and a phone and watch the signal fade, with the link speed stepping down wall by wall.
- [Why do AI agents need tools?](https://explainertools.com/originals/agent-tools/): Switch an AI assistant's tools on and watch it turn a guess about today's weather into a lookup.
- [How can a camera tell how far away something is?](https://explainertools.com/originals/depth-lab/): Drag a cyclist toward a pair of cameras and watch the shift between their two views grow as the distance shrinks.
- [How does Portrait Mode fake a blurry background?](https://explainertools.com/originals/portrait-mode/): Tap a photo to move the focus point and watch software blur each part of it by its distance in a depth map.
- [How do noise-cancelling headphones work?](https://explainertools.com/originals/noise-cancelling/): Slide an anti-noise wave against an engine hum and watch the two cancel. Let the timing slip and they add up instead.
- [Why do grandfather clocks have such long pendulums?](https://explainertools.com/originals/pendulum-lab/): Drag a pendulum longer and watch its swing slow. At about one meter, each swing takes one second, which is why clock cases are tall.
- [How does your phone camera focus?](https://explainertools.com/originals/focus-lab/): Drag a flower toward a phone camera and watch a tiny motor slide the lens until it runs out of travel at about 10 cm.
- [Why do deer freeze in your headlights?](https://explainertools.com/originals/deer-eyes/): Take the mirror out of a deer's eye and watch its eyeshine vanish. Why eyes glow in your headlights, and what biologists say about the freeze.
- [Why don't satellites fall down?](https://explainertools.com/originals/newtons-cannon/): Fire a cannonball faster and faster from a mountain top until the ground curves away as fast as it falls. Newton's cannon as a working model.
- [Why do eyes glow red in flash photos?](https://explainertools.com/originals/red-eye/): Slide a camera's flash away from its lens and watch the red return beam miss. A simplified model of why eyes glow red in flash photos.
- [What makes a sonic boom?](https://explainertools.com/originals/sonic-boom/): Drag a plane past the speed of sound and watch its sound rings pile into a cone that sweeps the ground. An interactive model of sonic booms.
- [Why do hurricanes spin?](https://explainertools.com/originals/hurricane-spin/): Drag a storm from north to south of the equator and watch Earth's spin curve its inflowing air one way, then the other. A sped-up Coriolis model.
- [Why do stars twinkle but planets don't?](https://explainertools.com/originals/twinkle/): Grow a point of starlight into a planet's disk and watch the twinkle average away. A simplified model of atmospheric scintillation.
- [How far away was that lightning?](https://explainertools.com/originals/thunder-timer/): Drag a lightning strike closer and count the seconds until the thunder arrives. The speed of sound, the 3-seconds-per-km rule and storm safety.
- [Should you switch doors?](https://explainertools.com/originals/monty-hall/): Play the Monty Hall game by hand, then run thousands of rounds with up to 100 doors. See why switching wins two times in three.
- [Why is paper so hard to fold more than seven times?](https://explainertools.com/originals/paper-folding/): Fold a paper strip again and again and watch each bend eat more paper. Britney Gallivan's folding limit, plus a stack that reaches the Moon.
- [Why does a cold glass sweat?](https://explainertools.com/originals/cold-glass/): Drag the humidity and the drink temperature and watch droplets form or vanish on a cold glass. An interactive dew-point model.
- [Why does a torn QR code still scan?](https://explainertools.com/originals/qr-code/): Tear, stain and scratch a real QR code and watch a real decoder still read it. Error correction you can break with your own hands.
- [Why do skaters spin faster with their arms in?](https://explainertools.com/originals/skater-spin/): Pull a spinning skater's arms in and watch the spin speed up while angular momentum stays locked. A segment model of a real spin.
- [Why does Mars seem to move backward?](https://explainertools.com/originals/mars-retrograde/): Drag the date through early 2027 and watch Mars loop backward against the stars of Leo as Earth overtakes it. Real orbits, real stars.
- [How do you throw a perfect spiral?](https://explainertools.com/originals/football-spiral/): Crank a football's spin and watch the same shaky release shrink from a wobbly duck into a tight spiral. Gyroscopic stability you can throw.
- [Why is the background blurry?](https://explainertools.com/originals/lens-lab/): Close the aperture and watch the background sharpen. Follow the light inside the lens to see why each far light lands as a disc.
- [Why does Starlink feel so fast?](https://explainertools.com/originals/low-orbit-internet/): Drop a satellite from 36,000 km to about 500 km and watch the round trip shrink from half a second to a few milliseconds, and why you then need thousands.
- [Why is the sky blue but sunsets red?](https://explainertools.com/originals/sunset-lab/): Drag the sun to the horizon. Its light crosses nearly forty times more air, and the blue scatters out before it reaches you.
- [Why does microwave food heat unevenly?](https://explainertools.com/originals/microwave-lab/): Spin the turntable and watch fixed microwave bands, about 6 cm apart, turn stripes of hot and cold food into rings.
- [How can a heat pump give more heat than it uses?](https://explainertools.com/originals/heat-pump-lab/): Drag the outdoor temperature down and watch a heat pump move heat in from freezing air, and why a bigger lift takes more electricity.
- [How does a hummingbird hover?](https://explainertools.com/originals/hover-lab/): Stop a hummingbird's wing from flipping and watch its back stroke push the wrong way. Hovering flight, slowed way down.
- [Why do propellers look bent on camera?](https://explainertools.com/originals/shutter-lab/): Spin a propeller and watch a phone camera read its sensor row by row, so straight blades come out curved.
- [Why do sunflower seeds form spirals?](https://explainertools.com/originals/sunflower-lab/): Turn each new seed by the same angle: 120° stacks seeds into three arms with gaps, while the golden angle packs them into 34 and 55 spirals.
- [Why do traffic jams appear out of nowhere?](https://explainertools.com/originals/traffic-waves/): Add cars to a ring road and tap one driver's brakes: on a quiet road it fades, on a busy one it grows into a jam that drifts backward.
- [Why do hot magnets lose their order?](https://explainertools.com/originals/ising-domains/): Drag the temperature and watch random thermal flips break up patches of matching spins. An interactive 16×16 Ising model, not a real material.
- [Keep squaring and adding. Does it escape?](https://explainertools.com/originals/mandelbrot-orbit/): Hold c fixed, start at 0, and slide the steps: watch one point square, add c, and stay within radius 2 or escape. A finite-step model of z² + c.
- [How many riffles mix a deck?](https://explainertools.com/originals/seven-riffle-shuffles/): Drag the riffle count and watch a 52-card deck cut and interleave, while the exact model shows how far every possible deck is from uniform.
- [Why mow the long way?](https://explainertools.com/originals/lawn-coverage-path/): Flip the mowing stripes on a model lawn. Both ways cut the whole lawn with 48 units of lanes, but one needs 3 U-turns and the other 5.
- [How could a car stick, then flip?](https://explainertools.com/originals/roadster-lab/): Move a fan car up a curved ramp to upside down. Push it with a jet. See when it holds, slides or falls off, then flip it with two jets. An illustrative model.

## Optional
- [All creators](https://explainertools.com/creators/)
- [Shorts and films](https://explainertools.com/videos/)
- [About ExplainerTools](https://explainertools.com/about/)
- [Privacy](https://explainertools.com/privacy/)
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