Officials on Tuesday said that while not all users were affected, they put the site into maintenance mode to investigate the problem. Many users reported the site to be slow or got no response.
Michael Marchand, a spokesman for the Washington Health Benefit Exchange did not identify the cause of the problems, but said high traffic volume was not the issue.
"I'm not so much disappointed because you don't know what you don't know. you always run the risk with any large scale deployment of this kind of not going correctly" Marchand told KOMO News.
"The phone number for people to call, 855-923-4633, is not affected, and people are still able to go to locations around the state in person.
Washington state's marketplace used Twitter to apologize and to thank users for their patience.
By mid afternoon, wahealthplanfinder.org was back online but running slow according to users.
Washington residents have six months to buy health insurance through the new exchange during the first enrollment period, which ends in March.
The state estimates about a million Washington residents do not have health insurance, or about one in seven people.
King County's Executive Dow Constantine is hoping to enroll all of King County's uninsured into the exchange.
"I have set the admittedly ambitious goal of full enrollment for our uninsured king county residents" says Constantine.
The state hopes to enroll 130,000 people for health insurance in 2014 and another 280,000 in 2015.
Another 325,000 people will be eligible to sign up for free insurance through Medicaid.
Under the Affordable Care Act, people who don't have insurance in 2014 will pay a fine when they file their federal income taxes in early 2015. The fines for people who ignore the new law are scheduled to increase over time.
"We want 6.5 million people to go to healthplanfinder to check it out," Marchand said Monday