Facebook Messenger has a half a billion users, even though most people initially hated it

In just a few short months since its controversial launch, Facebook's stand-alone Messenger app now has half a billion active monthly users.

"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," says Peter Martinazzi, Facebook's director of product management, in a blog post.

The largest social networking site announced in April that users would no longer be able to send or read messages on its main app and would be forced to download a separate app to chat with friends, send videos and make free calls.

This sparked backlash from users who hate when any changes are made to the popular social platform. The Messenger received negative reviews even after the app hit the number one spot in the iOS App Store. Many iPhone users were leaving one star ratings. Android users weren't happy about it either.

Users were not only outraged that they were forced download the app, but privacy concerns also surfaced. Some who downloaded the app claimed the app uses your camera to take pictures or record what you say with the phone's microphone.

Addressing the false rumors, Facebook says that the app does not turn on the camera or microphone when the user is not actively using the app.

Another rumor was that the app reads the user's call log and may share data. There were also claims that the app sends SMS messages with unexpected charges without confirmation, and the app reads personal profile information stored.

But even with high privacy concerns, 500 million monthly users have Facebook Messenger. While these numbers are high, as of September 2014, Facebook has 1.35 billion active monthly users alone. Head of Facebook Messenger, David Marcus, says his team is "going for a billion" users.

Facebook Messenger is not the only app doing well for the social network. WhatsApp, the messaging app that Facebook purchased for $19 billion, has 600 million active users.

Check out people's initial reactions to Facebook Messenger below.

Photo Credit: Kārlis Dambrāns