I once used a tool called "PAP Designer" ("Programm AblaufPlan" Designer), which had a great system for allowing you to put new boxes. But I am not sure it stil

I once used a tool called "PAP Designer" ("Programm AblaufPlan" Designer), which had a great system for allowing you to put new boxes. But I am not sure it still exists and fullfils the all needs, as a plain flow chart might not be all you need. You might want to add comment boxes and stuff. Otherwise I usually use yEd Graph Editor and haven't found anything better and lightweight yet.