How it works

Four ideas, each in service of one fact: a person blinks fifteen to twenty times a minute without meaning to.

The camera sees your eyelids — on your device
A face-landmark model runs inside your browser, in a background thread. It measures how open each eye is, thirty times a second. The video is analysed and discarded; it is never sent anywhere.
A blink language that ignores blinking
Anything under about a third of a second is a natural blink and does nothing. A deliberate closure of roughly half a second to a second and a half selects. Two of those in quick succession go back. Holding your eyes shut for over two and a half seconds puts the interface to sleep, so you can rest or watch television without it firing at you.
Calibrated to you
Setup watches a minute of your natural blinking, then asks for ten deliberate ones, and places the threshold in the gap between them. If there is no clean gap it says so and helps you find one. Thresholds keep adapting as you tire.
Scanning, then predicting
Options light up in turn; you blink when the one you want is lit. Rows first, then cells — three times faster than one by one. On the keyboard, word and phrase predictions are offered before the letters, and the rows most likely to hold your next letter are scanned first.

Safety is the product

Call help is never more than three selections away. It emails, texts and notifies your contacts at the same time, sounds an alarm on the device, and escalates if no one answers within two minutes.
If the camera loses you for a minute, your contacts are told.
Every character you type is saved as you type it. A crash or a dead battery never loses your words.
From every screen, there is always a way home using only your eyes.