Users lost access to their stored pictures, messages and contact details on the sites for a period of around 40 minutes.
Hackers are claiming to be responsible for crashing Facebook, Instagram and Tinder this morning.
Millions of the users were without access to their personal data on the dating site and social networks from around 6.30am.
Infamous online hacker ground Lizard Squad appeared to claim responsibility for the outage on Twitter.
A message posted from their account hinted other sites were down including MySpace, AOL Instant Messenger and Hipchat.
It said: "Facebook, Instagram, Tinder, AIM, Hipchat #offline #LizardSquad"
The sites, which claim to have more than 1.23bn monthly users, were unable to load for users who were trying to log on.
In a rare outage, visitors to the Facebook website at around 6.30am were greeted with a blank page while those on the app version were unable to update their news feeds.
Instagram was also thought to be down around the same time, a spokesperson confirmed this on Twitter but the tweet was later removed.
It said: "We're aware of an outage affecting Instagram and are working on a fix. Thank you for your patience."
Yesterday the hackers took over the website of troubled Malaysia Airlines, uploading a picture of a top hat wearing lizard and a rap song.
The front page of malaysiaairlines.com was replaced with the image of the reptile, who also sports a black tuxedo, a monocle and a pipe, together with a message which read 404 - Plane Not Found - an apparent reference to missing Flight MH370.