Shift calendar maker

Does anyone know an online tool (free🙂) for making a calendar for days on/days off? For example, 2 weeks on, 2 weeks off. Or other rotation.
I can always just get a paper calendar and start highlighting like every previous year, but figure there’s a better way.

The calendar on your phone does all of that.


I wound up downloading an app in which days can be color coded. Pretty much digital highlighter.