Scott Savitz, CEO of Shoebuy.com, said today he is resigning, effective immediately. Neither Savitz nor Shoebuy, No. 87 in the Internet Retailer Top 500 Guide, gave a reason for his departure, though both noted he is leaving the company in the midst of a healthy year for the retailer of footwear, apparel and accessories.

Savitz has worked as Shoebuy CEO since the company’s founding in 1999. The Shoebuy.com e-commerce site launched in January 2000, and Savitz stayed on through Shoebuy’s acquisition by InterActiveCorp., or IAC, in 2006. Since the site’s launch, Shoebuy.com revenue has increased, on average, about 50% per year, the online retailer says, although it does not report sales in dollars. Shoebuy sells about 1 million products from 1,500 brands. “I could not be prouder of what we have all built together and I know where I will always be buying my footwear and related apparel,” Savitz said this morning in an e-mail blast.

Savitz declined to give any hint of where he might work next, and he did not immediately respond to a request for comment. Shoebuy was keeping mum today about who would take over leadership. “A lot of people were surprised by Scott’s departure, so we aren’t announcing our plans for succession at the moment,” Shoebuy chief marketing officer James Keller tells Internet Retailer. (Shoebuy, on Tuesday, did name a replacement for Savitz; read that story here.)

He adds that Savitz today was wrapping up his business at the online retailer. “Scott is dedicating his time today to working with the various Shoebuy teams and individuals,” Keller says.