A spot I totally fell in love with is the little café
Latei. It's a really small place and also mostly visited by natives but definitely check it out! Their apple pie and fresh mint tea (seems typically too since you can get it nearly everywhere) are delicious as well as their sandwiches. You won't regret your visit between all the tea cups at the wall :)
For a only vegetarian option,
De Bolhoed is just your place. Also near the Anne Frank Museum, you get more rustic salads and quiches that are just as delicious as healthy.
For a coffee (or a hot chocolate as I would recommend) in the afternoon, spend some time in the
Van Harte which has a wonderful atmosphere to recover after a long shopping day in the little streets. (they have also lunch and diner, but we were there only in the afternoon)
And for the last café a spot that is located in an old pumping station. It's a nice place to spend some more time when you have to work (many take their computer with them) or simply wanna read a book - you'll have time there.