For #android users, make sure your #keyboard app (how you type text) is #FOSS or atleast #open-source. It is crucial for #privacy.

anysoftveyboard - need some configuration

florisboard - fairly simple and straightforward

tiny keyboard - lightweight

thumbkey - crazy squarish keyboard.

8vim keyboard - even crazier

simple keyboard - simple

simple keyboard (simplemobile suite -> fossify appsuite fork is better) also simple

unexpected keyboard

hacker keyboard adjustable

openboard - straightforward

you can install all of these transparant open-source keyboards using #F-Droid (or neo-store(alternative F-Droid client)), an open-source alternative for google play.