Some Swedish sites such as Ikea and Hemnet were also affected by disruptions, as were hospitals in Norway.
By 10:30, many of the affected sites were back up and running. Måns Jonasson, internet expert at the Internet Foundation, describes it as the internet having a hiccup.
"It cannot be ruled out that it is an attack, but it is probably a user error. It may have been an update that led to an outage," he says.
Cloudflare is one of the largest internet service providers in the world and many players use their servers. They also offer a kind of shield in front of websites from various types of online attacks.
As recently as a couple of weeks ago, several global internet services and platforms were affected by technical problems.
