With so many fashion tech startups popping up constantly, it can be hard to figure out which ones are actually cool and useful, especially when many of them are very similar. Last year, we were inundated with recession-friendly member’s only flash sale sites. This year, it’s all about adapting the methods of Pinterest and Instagram for fashion. Ecommerce is still big, but entrepreneurs are finding ways to make the shopping experience social rather than exclusive. One way a few smart companies are trying to get people to engage is by getting celebrities and fashion influencers like editors, bloggers and it girls on board in the beginning and letting the social, viral nature of their sites and mobile apps do the rest.

Click through for the 10 sites and apps that we think do the best job of this, including the new one the Olsens are using.