Purely CLI tools are harder to monetize. But I’ve seen REPL instances (which are command line in a way but interactive) monetized. The AMPL optimization langua

Purely CLI tools are harder to monetize. But I’ve seen REPL instances (which are command line in a way but interactive) monetized. The AMPL optimization language is monetized. The very expensive KDb+ language and database is monetized. Back in the day lots of DOS shareware tools like pkzip, etc were monetized as shareware.