According to DownDetector, the issues started at around 16:44 BST, and are affecting users globally.
Facebook is yet to comment on the outage.
The most popular social media apps around the world Facebook, Instagram, WhatsApp and Facebook Messenger have all crashed this afternoon
Users trying to access Facebook are greeted with an error message (below), with users of WhatsApp and Instagram able to view the apps, but new content is not appearing.
“Sorry, something went wrong. We’re working on it and we’ll get it fixed as soon as we can,” a message on the Facebook website said.