REDWOOD CITY -- Zazzle, a shopping website and customized gifts manufacturer, is hiring more than 800 people for the holiday season, anther sign of the growing popularity of online and mobile shopping.

The Bay Area e-commerce company plans to more than double its workforce to 1,300 employees by Thanksgiving, adding seasonal and permanent staff to its headquarters in Redwood City and manufacturing plants in San Jose and San Diego. Zazzle spokeswoman Diana Adair says the company is quickly growing and sees a spike in sales early in the shopping season -- well before other traditional retailers -- as the website expands its selection to include holiday cards, postage, wrapping paper, ornaments and other items shoppers look for weeks before Christmas.

The Zazzle manufacturing facility in San Jose stays open around the clock during the holidays, allowing online orders to be turned around in three or four hours, Adair said. Zazzle also partners with local merchants, including Rickshaw Bagworks in San Francisco, to sell custom designs for products such as handbags and water bottles, which brick-and-mortar retailers can sell in their stores.

Job applicants can email holidayjobs@zazzle.com.

Contact Heather Somerville at 510-208-6413. Follow her at Twitter.com/heathersomervil.