Privacy assistants aim to provide meaningful privacy recommendations to users. Here, we describe a web-based testing environment for smartphone privacy assistants called the “Mock App Store” (MAS). The MAS was developed to test a particular privacy assistant – the value-centered privacy assistant (VcPA) – which assists users in selecting applications based on their value profile. While the MAS was designed with the VcPA in mind, it could also be utilized to test other state-of-the-art privacy assistant technology.