Facebook’s standalone app Messenger has hit a milestone of 500 million monthly users, the company has announced.

Previously, Facebook users, which are well over a billion, could message their friends from within the core Facebook app, but now that option is only available to those who download Messenger. Facebook’s decision to add this extra step was met at launch with a lot of negative response.

“Since Messenger launched in 2011 we’ve been passionate about giving people a faster and more expressive way to communicate,” said Peter Martinazzi, director of product management, in a statement. “This is an exciting milestone but with a half billion people relying on Messenger to communicate and connect, it is also a reminder that there is so much left for us to do,” he added.

Last month it was reported that Facebook plans to ramp up efforts around its mobile apps to make them into successful standalone businesses.

“Over the next five years our goals are around taking our next generation of services – Instagram, Messenger, WhatsApp and search – and helping them connect billions of people and become important businesses in their own right,” CEO Mark Zuckerberg said during the company’s results presentation.