Heart Rate

Tap along to your pulse and read your beats per minute.

fx-991ES

A CASIO fx-991ES PLUS: natural display, exact answers, S⇔D.

XY Plane

Type y = … or a whole relation. Intervals, marked points, tables of values; drag to move, scroll to zoom.

Circuit Lab

Build a circuit and watch it work — current, voltage, gates and all.

Python

Real CPython in your browser. numpy, pandas, sympy, matplotlib and the rest of PyPI, fetched when you import them.

HTML · CSS · JS

Three panes and a live page. Type, and watch it change.

Scratchpad

Somewhere to think out loud while you study.