It's one of the most popular messaging services in the world today, with a staggering 900 million users worldwide.
But now, in order to comply with new EU data protection rules, WhatsApp is banning under-16s from using its platform in the European Union.
Currently users must be at least 13, but the Facebook-owned firm is changing the rules ahead of the introduction of the European General Data Protection Regulation (GDPR), which comes into force on 25 May,
The app will ask users to confirm their age when prompted to agree new terms of service in the next few weeks.
WhatsApp has not said how the age limit will be enforced.
At present, WhatsApp does not ask users their age when they join, nor does it cross-reference their Facebook or Instagram accounts to find out.
Fifth most popular social network with young users
According to a 2017 report by the media regulator Ofcom, about a third of all UK-based 12- to 15-year-olds active on social media use WhatsApp,
That made it the fifth most popular social network with the age group after Facebook, Snapchat, Instagram and YouTube.
WhatsApp said it was not asking for any new rights to collect personal information.
“Our goal is simply to explain how we use and protect the limited information we have about you,” the company said.
Facebook and Twitter have also been rolling out new terms of service ahead of the GDPR launch, in order to bring their businesses in line with the new regulations, which require clear consent from users to access their data.
The regulations give users greater powers to control how their data is used and the right to have data erased.
WhatsApp said the update ensured it could “meet the new high standards of transparency for how we protect the privacy of our users”.
It plans to keep the over-13 age restriction in the rest of the world.