Thousands of users across Europe, America and Canada are unable to connect to WhatsApp on both Android and iOS today.
People were unable to respond to existing chats, start new ones or use the messaging app's WhatsApp web service.
It appears the service went down at 16.28 GMT (11.28 ET) and resurfaced around 45 minutes later - only to crash again minutes later.
A live outage
map for all the regions in which WhatsApp is available can be found at website downdetector.
This revealed the outage spread across Europe and the US.
The map users a colour scheme to indicate where the reports are originating.
The main problem appeared to be that the app couldn't connect to the internet, even if the user had a working mobile or Wi-Fi connection.