Everything in the catalog

Computes SHA-512 digests of text or a file locally in the browser.

Decodes percent-encoded URL strings back to readable text.

Percent-encodes text for safe use in a URL.

Estimates the token cost of an image for OpenAI vision models from its width, height and detail level.

Loads a font file and shows each glyph with metrics and path data.

Turns Java package names into a visual folder tree.

Tests strong and weak acids and bases to see ion counts, pH and conductivity.

Uses area models to show multiplication and factoring of whole numbers.

Places masses on a plank to balance it and discover the lever principle.

Practice balancing equations by adjusting coefficients with a visual atom count.

Shines light through colored solutions to relate concentration, path length and absorbance.

Shows refraction and reflection of light between media and with prisms and lenses.

Adjusts temperature to show how blackbody spectrum and peak wavelength shift.

Assembles molecules from atoms to meet collection targets and view 3D structure.

Add protons, neutrons and electrons to a model atom and watch which element, charge and mass result.

Lets you assemble batteries, bulbs, resistors and switches into DC circuits and read meters.

Collides balls in one or two dimensions and checks momentum and energy conservation.

Mixes colored light to show how the eye perceives color.

Compares masses and volumes of blocks in water to explore how density affects floating.

Tracks energy as it moves between heating, light and motion in a set of linked systems.

Moves a skater on adjustable tracks to show kinetic, potential and thermal energy.

Balances scales to build intuition for solving equations.

Moves a magnet through a coil to induce current and light a bulb.

Pulls and pushes objects to explore net force, friction and acceleration.