It uses Facebook to pull in photos for a profile, as well as another signal to verify users. The League app uses LinkedIn to verify profiles, build profiles and block co-workers from your company seeing your profile (by blocking them in the matching algorithm). Working professionals is a bit vague, but largely people assume it means tech, startups, finance, law, medicine, executives or other white collared jobs with a career-minded focus. Similarly, the app has a relaxed screening process (for better or for worst) resulting in more overlap of users on apps like Hinge & Bumble. The naming alone sounds a bit elitist, but the screening process for the intentions is enough for people to ignore the stigma around the pretentious name.