A rush of issues were reported on Tuesday lunchtime United Kingdom time, as users reported being unable to load the page at all.
Facebook didn't immediately have an explanation about what was causing Tuesday's outage. However, it's rare for Facebook's entire family of apps to be spotty at the same time.
Facebook has more than 2.2 billion users worldwide, while Instagram - which is owned by Facebook - has more than one billion active users.
Users in the US and Europe began reporting that Facebook has been inaccessible since at least 8:15 a.m. ET.
The outage adds to a list of troubles that've been plaguing the company this year.
Reports of the outage first came in at about 8pm.
Both social media giants have been hit by major outages that left them refusing to load for some of their users.
Facebook released a statement Tuesday saying, "We are now experiencing issues that may cause some API requests to take longer or fail unexpectedly". Even Facebook took to Twitter to alert users the company was working on fixing the outage.