Twitter, which remained online, hosted users’ anger with #FacebookDown, #instagramdown and #whatsappdown all trending globally.
It was not immediately clear what caused the outage or how long the platforms would be down.
The service interruption comes just a month after Facebook, which acquired Instagram in 2012 and WhatsApp in 2014, experienced a severe outage.
Its apps were unavailable for hours. A day later, Facebook attributed the outage to a “server configuration change” and apologised.
There are more than 1.52 billion daily active Facebook users, according to the social media network’s website.