Between 1995-1997, he was employed at NeXT as a developer and trainer. In 1997, NeXT merged with Apple Computer. Hillegass elected to leave his role to start his own dot-com business.
In 2000, he was then contracted by Apple to help train their software developers in the Cocoa application programming interface (API), an evolution of the NEXTSTEP API. This led to the creation of Big Nerd Ranch, a professional services company that originally worked only with Apple technologies.
Today, Big Nerd Ranch provides end-to-end mobile solutions for a range of app development projects, including iOS, Android, backend, frontend, Cocoa and UX/UI design.