There's no need to fret if you lost your invite code to decentralized Twitter spinoff Bluesky - the service has thrown open its doors to all comers.

The social network had been in an invite-only beta since it debuted with an iOS app in February 2022. On Tuesday the Bluesky team announced it's now open to all.

The outfit also teased a forthcoming "labeling service" that will allow organizations and individuals who want to moderate content to create their own labels - which could be used, for instance, to fact-check posts and amend content.

"Under the hood, centralized social sites use labeling to implement moderation - we think this piece can be unbundled, opened up to third-party innovation, and configured with user agency in mind," Bluesky CEO Jay Graber explained last year. "Anyone should be able to create or subscribe to moderation labels that third parties create."

On Monday, Bluesky published a paper [PDF] detailing the AT Protocol that underpins the platform.

A brief history of Bluesky

For those not among the "more than three million people" that Bluesky claims are using the platform, the site is, on its surface, a Twitter clone - not a surprise given its origin as an initiative started towards the end of founder Jack Dorsey's era in charge of the avian network.

By 2021, Bluesky had spun off into its own public benefit company under the collective ownership of Graber and other Bluesky team members - at least before its first seed round. The service's FAQ still lists Graber and the Bluesky team as the owners of the biz, albeit with a board including Dorsey.

In 2022, the still-linked-to-Twitter Bluesky published a prototype of what it called the Authenticated Data eXperiment (ADX) protocol, which it described as a "self-authenticating social protocol" on GitHub. That experiment has since evolved into the AT Protocol that forms the backbone of the Bluesky Social platform.

If you're wondering what differentiates the AT Protocol from Mastodon's ActivityPub, that's a good question. Bluesky explains the primary reason as one of account portability - an issue that anyone who's used Mastodon can attest is a bit of a hassle.

"We consider portability to be crucial because it protects users from sudden bans, server shutdowns, and policy disagreements," the AT Protocol FAQ states. "Our solution for portability requires both signed data repositories and [decentralized identifiers], neither of which are easy to retrofit into ActivityPub."

Bluesky's ultimate goal is a network of social apps that can all talk to each other - comparable to the "fediverse" but with more control at the user level through easier account migration and other usability improvements.

One of those usability improvements is Bluesky's "marketplace of algorithms." The platform doesn't have a single master algorithm that determines content presented to users, instead favoring customizable algorithmic feeds that can be shared with other users.

"For users, the ability to customize their feed will give them back control of their most valuable resource: their attention," Graber wrote.

Bluesky became wholly independent of Twitter in late 2022 after "Twitter chose to sever the service agreement with Bluesky, and Bluesky agreed," the Twitter spinoff explained. It's not clear if the service agreement severance happened before or after Elon Musk acquired Twitter - we've sought clarification but have not received a reply at the time of writing.

If Bluesky's numbers are accurate, it has grown rapidly of late. The platform only reached one million users in September, and with its public launch today has announced over three million users. It's not clear how many active users the platform has, though web analytics outfit Similarweb estimated it was somewhere in the neighborhood of 583,000 in October 2023 - putting it at around half of Mastodon's reported one million monthly actives.

Whether Bluesky will be able to catch up with its big-name competitors - Elon Musk's X, which is believed to have somewhere in the neighborhood of 335 million monthly active users, or Meta's Threads, which Mark Zuckerberg claimed [PDF] in the most recent quarterly earnings call had reached 130 million monthly active users - remains to be seen.

The recently rebranded service has some features that could make it a nice place to land if it gets traction. With the doors now open, it can't hurt to flit on over and at least give it a try. ®

https://www.theregister.com//2024/02/06/bluesky_social_media_opens/