Admitted introvert Angie Hicks, co-founder of Angie’s List, seems to be everywhere these days — on billboards, radio spots, and TV. It’s a role she’s getting more comfortable with, but would never have imagined 20 years ago when she was knocking on doors in Columbus, Ohio, to sign up the very first member for “Columbus Neighbors,” a telephone referral service that published reviews of service providers.

But her Midwestern persistence paid off. The company grew fast, buying out an Indianapolis competitor, and migrating to the Internet. In 2002, Angie’s List made Inc.’s list of the 500 fastest-growing companies.

Fast-forward to 2015. The publicly traded $350 million company is an established national brand with more than 3 million subscribers, 700 service categories, and nearly 2,000 employees. But the original premise remains. “We want homeowners to have great outcomes when they hire a provider,” says Hicks. Those not up to snuff are put into a “Penalty Box,” a hiring-beware zone, she notes.