Act Four is an iPhone app by AIV LLC that aims to guide both newbies and seasoned espresso enthusiasts in achieving the perfect cup. For those new to espresso making, the app offers a video-guided workflow mimicking professional baristas' steps. It provides analysis on brew speed and taste to help adjust your equipment and recipes for that ideal cup.

For espresso pros, Act Four focuses on taste adjustments. It helps in fine-tuning Brew Weight and Brew Timing based on the tasting experience, with each brew refining the process. The app's hands-free approach allows for automatic tracking of recipe, preinfusion, brew, and flow rate, making the process seamless and efficient.