How it works
One character per cell
Each character sits in its own cell of a monospaced face, with every other cell lightly shaded and its position numbered underneath, so a Wi-Fi password or a booking code can be read out and checked one character at a time.
Digits and symbols can take their own colours, which tells 0 from O and 1 from l at a glance. Spaces show as ␣ so you can count them.
How the size is chosen
With Fit, the tool tries sizes from 360 px down to 28 px in steps of 4 and keeps the largest at which every cell fits the display without scrolling. A word never breaks across rows: when it would, it moves to the next row whole, and the size is capped so the longest word fits on one row.
Manual lets you set the size yourself; the word cap still applies. Marquee runs the text along one line instead, at the height of the display but never so large that fewer than three characters show.
cell width = size × widest advance + padding; cell height = size × 1.2 + padding (+ 18 px for positions)
Full screen
Full screen hands the display to the browser's fullscreen mode; the size is worked out again for the whole screen. Press Esc to come back. You can keep typing while it is full screen.
