Instagram and Facebook went down on Friday afternoon, with users around the world reporting issues.
Down Detector said the disruptions began at about 1336GMT, and more than 3,000 incidents were recorded on the site.
Among Instagram users who reported problems, 68% said the app was not working properly, while 12% said they were unable to log in.
Another 10% said the issue was related to the server connection.
On desktop, users were shown a simple error message saying: "Sorry, this page isn't available."
Meanwhile, hundreds of frustrated users turned to US social media company X to talk about the outage.
