Instagram just keeps on growing, on Wednesday announcing its monthly user base has soared past the 300 million mark.

That means the photo- and video-sharing service has added a whopping 100 million users in the last nine months alone, and is now bigger than Twitter, which at the last count a couple of months back had some 284 million users.

Launched as an iPhone app four years ago, the service proved popular pretty much right away, hitting a million users in just a couple of months. In a year it had 10 million, and when the app landed on Android in April 2012, the buzz was loud enough for Facebook to drop a billion bucks for it.

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Announcing the 300-million milestone on the Instagram blog, CEO Kevin Systrom wrote, “Over the past four years, what began as two friends with a dream has grown into a global community that shares more than 70 million photos and videos each day.”

The growth is great news not only for Systrom but for Mark Zuckerberg too, for it was very much the Facebook CEO’s idea to acquire the startup two years ago – a move that some speculated would actually ruin the app.

Zuckerberg’s push into mobile in recent years is certainly paying off, with growing ad revenue being delivered via Facebook Messenger (500m users), WhatsApp (600m), Instagram (300m), and Facebook itself, which has a colossal 1.35 billion users across all platforms.

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Moving forward, Systrom says his service is set to introduce a number of new features in the coming days, including verified badges for celebrities, athletes and brands (sound familiar, Twitter users?).

The CEO said his team is also set to start deleting the spam accounts that it’s been deactivating throughout this year, which could affect some users’ follower counts.

“Most of you won’t see any impact,” Systrom wrote in his post. “If you’re one of those who will see a correction, you will receive a notification in the app directing you to additional information.”