Screenshot by ZDNETBluesky saw its user count hit and surpass 20 million on Tuesday, a major milestone for a social network that officially launched in February of 2023 on an invite-only basis.More people have been flocking to Bluesky lately, with many likely joining as an alternative to Elon Musk’s X. In the week following the US presidential election, Bluesky snagged more than 1 million new members for a total of almost 15 million users, a company spokesperson told The New York Times last Tuesday. Also: How to get started using Bluesky Social: Everything you need to knowFrom 9 million in early September and 12 million around mid-October, Bluesky showed a surge in growth in November, adding more than a million in one week and then a million more in just 24 hours. You can watch the numbers continue to climb in real time here.Bluesky’s explosive growthOn the mobile front, Bluesky’s iOS app is currently at the top of the charts among all free apps in Apple’s App Store. As Number 1, it’s ahead of other popular free apps like Threads, ChatGPT, Google, TikTok, and Instagram. It’s also topping the Android charts. At the same time, X has watched its numbers dwindle. This past April, the Musk-owned platform had around 611 million users, according to stats from Statista and other sources. At last count in September, that number had dropped to 586 million. The decline has been especially felt in the US and UK, according to The Financial Times, as spotted by Social Media Today. But even in the EU, the number of X users fell by 5% over the first half of 2024.Also: 7 things to know about Bluesky before you join – and why you shouldIn contrast, Bluesky has enjoyed steady and sometimes sudden growth in its audience since its launch around two years ago. This past February, the user count surged by more than 800,000 after the network removed its invite-only requirement. Last month, the audience jumped by half a million in just one day. But that was just after X activated a new feature to let blocked accounts still see posts from the person who had blocked them.Why are people ditching X?That brings us to the present day. Why another sudden exodus of users from X to Bluesky? There are a few likely reasons.Also: How to migrate from X to Bluesky without losing your followersThere are the usual complaints about X’s increased toxicity and polarization, probably more keenly felt during the run-up to this year’s US presidential election. As people with different political and social beliefs have duked it out on X, others caught in the crossfire have likely left for safer ground.Bluesky has “become a refuge for people who want to have the kind of social media experience that Twitter used to provide, but without all the far-right activism, the misinformation, the hate speech, the bots and everything else,” media scholar Axel Bruns said, according to The Guardian. “The more liberal kind of Twitter community has really now escaped from there and seems to have moved en masse to Bluesky.” More