We use Tandem extensively: the killer feature is that during screenshares you get to control a pointer that the other person can see on their screen, which makes pair programming over Tandem feel basically the same as in person.
It was especially useful when onboarding a dev onto a new section of code that they had never touched before, and also when unblocking someone who was having trouble learning to use the IDE.
It was especially useful when onboarding a dev onto a new section of code that they had never touched before, and also when unblocking someone who was having trouble learning to use the IDE.