The company recently announced that it would stop charging customers a $1 subscription fee. WhatsApp had previously given people just one free year of the service before charging the $1 annual fee.
News of the change was made in a blog post on the WhatsApp website.
The company, which is owned by Facebook (FB, Tech30), said it had nearly a billion customers around the world who use the app to stay in touch with friends, family and even patients.
WhatsApp said it had decided to stop charging because "as we've grown, we've found that this approach hasn't worked well" -- many users don't have a debit or credit card. Read more on money.cnn.