Surprisingly, the once-loathed mobile messaging app from Facebook is now being used by more than 500 million people.

Since it was launched in 2011, Facebook Messenger has become a part of people’s way of communicating with friends and family. However, last summer, the social network decided to spin off the messaging feature into a standalone app and force its mobile users to download it to send private messages, which led to a massive outcry from its members.

Probably for this reason, Facebook director of product management Peter Martinazzi called the user base growth as “an exciting milestone.”

“Messenger was the first of our standalone apps, and unlike our core Facebook apps, it focused on one use case – messaging,” Martinazzi said in a blog post.

He added:

“With Messenger, you can reach people instantly. It is just as fast as SMS but gives you the ability to express yourself in ways that SMS can’t. You can send stickers or vides, take selfies, chat with groups and make free calls.”

Users were initially discouraged to download the Facebook Messenger app for fear that their conversations might be recorded and used against them. Apparently, the app has a number of alarming permissions, such as allowing the app to call phone number without the user’s intervention or allowing the app to read personal profile info store on the user’s device.

Facebook tried to explain the logic behind those permissions, pointing it will be impossible to enable certain features without access to the device’s microphone, camera, etc. For instance, to allow users to make direct voice calls, Facebook Messenger will need permission to use the device’s microphone.

When asked during the first Facebook Community Q&A last November 6 why they forced users to download the app, Mark Zuckerberg answered “we needed to build a dedicated and focused experience” for messaging.

Whether or not that helped, Facebook users have obviously accepted the necessity of using Messenger, given that half a billion people already have it in their mobile phones.