Billionaire Mark Cuban backing a startup is not, on its own, a big story. He’s done it hundreds of times. But I was interested in this particular investment highlighted by Sarah Perez in TechCrunch:

Skylight, a startup taking on TikTok with a more open alternative, is launching its mobile app to the public on Tuesday after just 10 weeks of active development. The app, which is backed by Mark Cuban and others, is now one of many to build on top of the AT Protocol — the same technology that underpins the social network Bluesky and a growing number of other apps.

Developed by co-founders Tori White (CEO) and Reed Harmeyer (CTO), Skylight offers a short-form video app experience with many familiar features, including an in-app video editor; the ability to comment, like, and share videos; set up your own user profile; and follow others.

(You can download Skylight for iOS and Android now. It…looks like an underpopulated TikTok clone — but one I could log into with my Bluesky account.)

This stood out to me for two reasons. First: Have you remembered that TikTok is scheduled to be banned again on Saturday? One of the largest media platforms in the country, just disappeared into the ether? And that its only likely path for survival is for owner ByteDance to sell it to a set of billionaires and hedge funds handpicked by Donald Trump? (“We have a lot of potential buyers. There’s a lot of interest in TikTok. The decision is going to be my decision,” he told reporters over the weekend.) 2025 so far has presented so much political sensory overload that I feel like the president brokering the sale of the No. 1 source of news for young Americans has almost slipped people’s minds! (The administration’s point men for the sale have been J.D. Vance and Michael Waltz; one wonders if someone accidentally cc’d Xi Jinping on their Signal chats.)

But the second reason is that it’s another sign of momentum for the AT Protocol, that tech layer underlying Bluesky. You may remember that back in 2022, when Elon Musk bought Twitter, there was a surge of interest in a different alt-Twitter called Mastodon. Its key selling point was its underlying decentralization, thanks to being built on a protocol named ActivityPub. Apps built on ActivityPub could connect to and share information with other ActivityPub apps — so, for instance, a person’s social media posts on App A could also be made to appear inside App B or App C. This universe of shared ActivityPub apps was named the Fediverse, and people were excited because it was a strike against the control of important digital platforms by a single dude. If your favorite app for posting was bought by, well, someone you don’t like, your data and posting could just move to another app.

ActivityPub had a few key advantages. It was an official standard of the W3C, the international body that sets (or tries to set) these sorts of things. Mastodon, its flagship app, benefited from that big anti-Musk outflow in 2022. And a number of media platforms have worked to integrate with the Fediverse, from WordPress to Flipboard to Threads to Ghost.

But the integrations have been thinly adopted by users. Mastodon’s 2022 surge has been followed by a pretty steady decline in active users and servers. (Its decentralized nature makes it difficult to get accurate numbers, but it seems to have about 7.7 million user accounts and 880,000 monthly active users.) And Mastodon remains stubbornly complex to use — even to sign up for! — for typical users, limiting its appeal mostly to the technically savvy. Other apps built on ActivityPub — Reddit clone Lemmy, YouTube clone PeerTube, blogging platform Writefreely — are niche interests at best.

Meanwhile, Elon Musk’s continuing chokehold on American life sparked another mass Twitter exodus in November, when Trump was elected president. But the beneficiary this time was a different alt-Twitter, Bluesky, built on the aforementioned AT Protocol. Bluesky grew much faster than Mastodon and has sustained that growth; today it has nearly 34 million user accounts and something like 1.6 million daily (not monthly) active users. And while both protocols have their (vigorous) defenders, many argue that AT Protocol’s more recent origins have enabled a more user-friendly setup, with more granular control over services and better identity portability.

So, will AT Protocol be able to build out something like the Fediverse dream of 2022? It’ll be difficult, but I think it’ll bring some real advantages to the fight. For one, Bluesky’s popularity will offer a better jumping-off point for other apps. “Login with Bluesky” is a more useful pitch than “Login with Mastodon” ever will be. For another, the growing interest in AT Protocol seems to be more focused on building new apps than in integrating old ones — which suggests there’ll be more people invested in seeing the protocol succeed.

And finally, the TikTok situation offers a unique opportunity to gain the attention of a large group of disgruntled users. Remember when TikTok shut down briefly in January, driving tons of users to a Chinese app named Xiaohongshu or RedNote? Another shutdown could easily have the same effect on something like Skylight. (Or any of the other several TikTok clones built on AT Protocol.) And while I don’t expect TikTok to disappear this weekend, if a bloc of its users deems its new owners too pro-Trump or otherwise unacceptable, they’ll also be looking for alternatives. The campaign Free Our Feeds, announced in January, plans to raise $30 million over three years to “save social media from billionaire capture” and build a new ecosystem on the AT Protocol. Indeed, Skylight connected with Cuban after he expressed interest in January in supporting an AT-based TikTok clone.

Where’d Cuban do that? On TikTok, naturally.

@buildwithtori @Mark Cuban let’s build the AT Protocol TikTok together! #stitch #tiktokban #tiktok #tiktokrefugee #atprotocol #bluesky #socialmedia ♬ original sound – BuildWithTori