Scores of users from India, South Africa and the United Kingdom took to Twitter to voice their dismay.
There is no clarity as to what led to the problem.
Its official Twitter status account for example which is supposed to Tweet when the service is experiencing problems, appears to be no longer updated.
WhatsApp has faced similar widespread outages this year, including for several hours in May.
WhatsApp is yet to issue a statement or reason for the service being unavailable.
Whatsapp is finally updating its new feature "Delete for Everyone" so that might be the issue for the server down.
This is not the first outage that WhatsApp has suffered in 2017. On assurances of developers, users can now share data about their location with the chosen circle of people.
Twitter user @AdOketch said: "Many people have died due to #whatsappdown because they can't forward the chain message to their 10 friends!" (Yes, I know how typical of us millennials) I was sending it via WhatsApp and the images just wouldn't send.