This document describes Happen, a tool that allows users to quickly test prototypes and get feedback from real users through mobile apps and websites. Happen addresses the problem that traditional user testing takes 6-12 months and tests prototypes on the wrong audiences. With Happen, users can create prototypes, add tasks for testers to complete, and receive results within 1-2 days from their own targeted audiences. Happen works by integrating with mobile apps and websites, allowing users to complete tasks and earn rewards. This lowers the cost of user testing for clients while allowing publishers and participants to earn from completed tests.