Types text into Morse code and blinks the phone's flashlight (rear torch). Needs HTTPS and Chrome on Android. iOS blocks torch access from the web.
Morse: dots and dashes appear above as it transmits. The flashlight tracks in real time.
Works on Android Chrome. On iOS, try pointing the camera at the Morse Listener demo instead — the screen brightness approach won't work for torch, but this app can still drive the screen white for a visible flash (see note below if torch fails).