The extent of the outages was unclear but both sites were back online by 3 p.m. PT.
"We're aware of some issues affecting our servers and are working to address them now. Thanks for your patience and hang tight!" Vine said on its Web page.
Instagram's site carried the following message: "Sorry, we couldn't complete your request. Our team has been notified and will investigate as soon as possible."
Update: Both Instagram and Vine, as well as Airbnb, Flipboard and other sites, were impacted due to a problem with hosting provider Amazon Web Services.