The Kalverstraat is the biggest shopping street in the center of Amsterdam. Here you can find all the most popular (mainstream) stores. If you cross the Dam you can also find more stores at the Nieuwendijk. When you walk in the direction of Leidseplein, there are some more stores in the Heiligeweg and in the Leidsestraat as well.
If you’re more interested in small boutiques, vintage stores, and less known clothing the 9 Streets (9 Straatjes) and Haarlemmerdijk are great places to shop.
And lastly, when you’re into high-end fashion and money isn’t an issue, the P.C. Hooftstraat is your perfect shopping street!