The SQA is also considering ditching the laborious snail-mail, and scanning scripts for markers.
Anton Colella, director of qualifications, said the online tests will be launched this autumn in as yet unnamed subjects and run over the next two years. This would require "massive investment".
Pupils were already working with software packages that give immediate diagnostic feedback and there could be a demand for more online assessment.
The authority is not yet considering automated marking, although this would be possible in multiple choice papers. "You can't automate the marking of an English composition," Mr Colella said.