Facebook Messenger, the social networking giant’s standalone messaging app, has reached 500 million monthly users, up from 200 million in April.

The company said in a post on its site on Monday that in light of the news it was “more committed than ever to make it the best possible messaging experience.”

Launched back in 2011, the cross-platform app, which currently sits in the iOS store with a rating of just 1.5 stars, has been rapidly building up its user base since the summer when the company pulled the plug on messaging within its main mobile app.

The decision proved controversial, with many users feeling they were being pushed into downloading the software when they’d been perfectly happy messaging from within Facebook’s main app.

Related: Paper 1.1 continues Facebook’s evolution on mobile

A question on the matter was the first one raised at the social networking company’s inaugural public Q&A held last week at its Menlo Park base in Silicon Valley.

Described as “one of the most popular questions” among those who submitted posts to the event’s webpage, Zuckerberg was asked, “Why did you force us to install Facebook Messenger?”

The company boss told the audience he understood that asking the service’s community of more than a billion people to download another app was “a big ask,” explaining that it was necessary because “we could never deliver the quality of experience as just a tab in the main Facebook app, and that if we really want to focus on serving this well, we needed to build a dedicated and focused experience.”

More mobile apps

At the start of this year, Zuckerberg made no secret of the fact that the company was set on launching more standalone smartphone apps as it seeks to please investors with growing mobile ad revenue. The CEO described the expansion into mobile as “a three-year initiative” geared toward “building all kinds of new experiences for sharing.”

The company said on Monday that reaching half a billion users was “an exciting milestone” for its messaging app, adding, “With half a billion people relying on Messenger to communicate and connect, it is also a reminder that there is so much left for us to do.”

Related: Facebook plans more smartphone apps as mobile revenue rises