Groupon is a group buying website in the United States. It is a combination of e-commerce, web2.0, Internet advertising and offline models. It was established in November 2008. Its business focus is group buying by netizens, which is a new online shopping model that has become more popular in recent years.

Woot was one of the first group-buying websites in the United States to launch the concept of "group-buying once a day". It was founded in 2004 and is headquartered in Carrollton, Texas. It mainly sells consumer electronics products; on June 30, 2010, it was Acquired by Amazon for $110 million in cash.