Boxed CEO Chieh Huang says the company's biggest challenge in its early days was not having enough manpower.

"When we used to have those deluge of orders, we used to empty the entire corporate office, get a bus, and bring them here to the fulfillment center," Huang says.

Boxed packages and ships bulky items to customers directly from its warehouses, and is taking on the likes of Amazon and Costco.

The company started in 2013, in Chieh's parents' garage. Since then, it's expanded to four fulfillment centers and has turned to automation to help it keep up with demand. Boxed just finished fully automating its headquarters in Union, New Jersey, and saw its picking productivity increase by 600 to 700 percent.

Surprisingly, the company was able to keep its entire workforce thanks to retraining.