It was fairly easy to find. It was right off of the Dam Square so it was filled at the time with other Americans - the hostess was very friendly about checking which items on the menu were Vegan friendly - though only three or four of the menu items looked to be so.
You should ask though, as nothing is marked as being specifically Vegan.
I had a delicious Humus sandwich on brown bread and a chai tea with soya milk.
The service was slow but very friendly - I chalked that up to Amsterdam cafe style, which was fine because I wasn't in a hurry.