Booking reservations and buying tickets with friends can be a pain: finding the right events, exchanging myriad links and emails, coordinating schedules. “And then one person always gets stuck footing the bill for everyone else, and has to worry about collecting payments and cash from their friends afterward,” says Jared Hecht. “It ruins the experience.”

Enter GroupMe, the startup Hecht cofounded in 2010 with Steve Martocci, which enables users to easily classify offline social networks into online groups (friends, coworkers, yoga buddies), and share messages and media.