According to a source who wished to remain anonymous, the app was used between 2014 and 2016 to help Uber lure drivers away from Lyft. The existence of Hell was kept secret, save for a few top executives at Uber and a small number of people working on the program.

 Uber first created a bunch of fake Lyft rider accounts and spoofed their locations. They’d then get information about multiple nearest available drivers and eventually see how many Lyft drivers were available for rides at any given time across a city, as well as where they were and how much trips would cost.

It gets better (or worse, depending on how you look at this): Uber was able to pick up a persistent numbered ID that was tied to each individual driver when they were gathering information about rides available nearby.

It used those to figure out drivers’ habits, such as when in the day and week they drove for Lyft and, by matching their location data with that of Uber’s drivers, it could figure out which of them drove for both services, and then attempt to lure them away from Lyft by offering special bonuses when they hit a certain number of rides per week.

Uber reportedly built a secret app to track Lyft drivers