Julep Beauty, a cosmetics and nail polish e-retailer, has raised $30 million in a Series C funding round, it announced this week. The company says it will use the funding to further propel its rapid e-commerce growth—the e-retailer says its web sales tripled in 2013, but it does not disclose sales figures.

New investors Azure Capital, Madrona Venture Group and Altimeter Capital, as well as existing investors Andreessen Horowitz and Maveron, participated in the round. The new investment brings Julep’s total venture funding to $56 million since 2012.

Julep asks for customer feedback via forums and social networks such as Facebook and Twitter, and uses this feedback to determine some of the products it will make and sell, a technique called crowd-sourcing. That allows the e-retailer to introduce new products 10 times faster than other brands that rely on more conventional market research methods, it says. Julep also uses customer feedback from online focus groups and real-world brainstorming sessions in the development process.

“Julep has truly figured out how to deeply engage women where they already are—social, mobile and web—and leverage those channels to bring customers into the product innovation process,” says Julie Sandler, a principal at Madrona Venture Group.

Founded in 2007 by former Starbucks executive Jane Park, Julep started selling its products through an online subscription program and on its e-commerce web site. The retailer also owns four beauty parlors in Washington state and  sells its products in such retail stores as Sephora and Nordstrom, and through TV and web retailer QVC Inc., a unit of Liberty Interactive Group, No. 5 in Internet Retailer’s 2013 Top 500 Guide.

Sephora USA Inc. is No. 119 on Internet Retailer’s 2013 Top 500 Guide and Nordstrom Inc. is No. 28.