QR Code

Three big finder patterns tell a camera where the code is and which way up it sits, and Reed-Solomon error correction lets it lose up to 7, 15, 25 or 30 percent (levels L, M, Q and H) and still read back. Masahiro Hara's team at Denso Wave invented it in 1994.

Here every dark module is a crisp cell of splats, in one of seven styles and in a color theme or a country's flag colors, always with the contrast a camera needs. The splash reads its own picture back to check that it scans. Tap it and the modules around your finger are knocked loose and snap back; the Splash tab has eight more motions, each ending on a code that scans. Alive moves colors through the code at the speed you choose, and every frame still scans, because each module keeps nearly the same lightness. Your text never leaves your device.

Controls made by Ryan Kamp, MIT.