The private Scottsdale, Ariz., company's own site was working but sites it operates on behalf of customers were blocked in late afternoon. GoDaddy has eight large server farms in the U.S. as well as one in India.
The company tweeted it was "aware of the trouble people are having with our site" and urdged customers to monitor Twitter for more information.
In last winter's controversy concerning the proposed Stop Online Piracy Act (SOPA) in the U.S. Congress, GoDaddy was targeted because it supported the law, which was championed by publishers and Hollywood studios. The law remains unpassed in Congress.