This is because in 2014, some members of Congress filed an application to ban online gambling. Online sports betting operators could not offer services until 2018.Local laws allow any resident who is at least 21 years old to play at DE online casinos. In 2013, three global operators (Scientific Games, 888 Holdings, and Williams Interactive) applied for a licence and began offering casino games over the web. This law also made online sportsbooks legal. In 2012, the law came into force allowing Delaware casinos to offer their services over the internet. In fact, Delaware is the first state in the United States to make online gambling legal. The short answer is yes: online casinos in Delaware are legal.