Instagram’s new Threads app has already surpassed 100 million users, meaning it reached the milestone dramatically faster than even ChatGPT. OpenAI’s chatbot passed the mark after two months, but Threads, which only launched on Wednesday, got there in a matter of days. The number of users can be found in the Instagram app, which tracks the size of the Threads userbase.

Threads proved to be an early hit almost immediately. In the first two hours, it hit 2 million users and steadily climbed from there to 5 million, 10 million, 30 million, and then 70 million. The launch has been “way beyond our expectations,” CEO Mark Zuckerberg said on Friday.

On Monday, Zuckerberg said in a Threads post confirming the milestone that the growth was “mostly organic:”

Instagram head Adam Mosseri also posted about it, likewise noting that it took just five days to get there:

Users aren’t just signing up: they’re posting, too. As of Thursday, my colleague Alex Heath reported that there have already been more than 95 million posts and 190 million likes shared on the app.

That said, Threads is still in its infancy, and we’ll have to wait and see if it captures the same cultural cachet that Twitter once did. Meta isn’t specifically targeting trying to replace Twitter, according to Instagram head Adam Mosseri, and the company isn’t going to actively encourage politics and hard news on the platform, but it could end up being the place people go for a conversation-based social media platform. And while Meta “couldn’t be more psyched” about how the launch week has gone, “we don’t even know if this thing is retentive yet,” Mosseri said.

Although the numbers aren’t directly comparable, as of last November Twitter had around 260 million monetizable daily active users, per a tweet from owner Elon Musk at the time. More recently, The Wall Street Journal reports it’s been telling advertisers that it has around 535 million monetizable monthly active users. But external data suggests Twitter’s traffic has been on a downward trend in recent months, with CloudFlare CEO Matthew Prince posting to say traffic is “tanking.”

Update July 10th, 3:58AM ET: Updated to add data on Twitter’s user numbers.

Update July 10th, 9:55AM ET: Updated to embed Threads posts from Zuckerberg and Mosseri about the milestone.