DuoKeyboard

This add-on adds automatic keyboard switching on duolingo based on the user preferences.
Multiple keyboards are supported covering most of the courses including Czech, Danish Dutch, English, Esperanto, French, German, Hebrew, Hindi, Italian, Portuguese, Russian and more.

For several languages it is possible to choose different keyboard layouts.

TELEX, VNI and VIQR input is supported for Vietnamese learners.

Additionally a cheat sheet can be shown on screen to assist in learning the keyboard layout.

For instruction on how to use, see "How to use" in the option page by clicking on the DuoKeyboard icon at the top right of your browser after installing.