Users around the world are reporting problems connecting and sending messages through WhatsApp.
The company said it was working on the issue via its Twitter feed.
"You may be experiencing some issues using WhatsApp at the moment," said the tweet. "We’re aware and working to get things running smoothly again. We’ll keep you updated and in the meantime, thanks for your patience."
It later tweeted that the service was back up and running.
Outage website Down Detector saw a peak in reports of problems with WhatsApp at 12.08am Friday UAE time.
Several users used the platform to report issues with sending messages and making calls through the popular messaging service.