Pen's Blog
ActivityPub vs. AT Protocol: Competing Standards or Corporate Sabatoge
Feb 12, 2024
As of February 6th, 2024, BlueSky, the decentralized social media platform, has gone public. Not on the stock market, but on the sign up market. Before, BlueSky was an invite only platform, but now, that restriction has been lifted. However, with BlueSky opening to the general public, I began to think of its competitor protocol, ActivityPub, and the differences between the two. If you haven’t heard about decentralized social media protocols, then you either haven’t been paying attention, or simply don’t run in circles as fluent in tech as mine are. For the purposes of this post, we will only be covering ActivityPub and the Authenticated Transfer protocol. So, what is the difference between the two, not technologically, but socially, and is it safe to trust the Twitter funded Bluesky?
Let’s start with the older protocol, ActivityPub. Introduced in 2018, activitypub is W3C’s answer to social media. If you don’t know what the W3C is, I wouldn’t blame you. W3C, or the world wide web consortium, was founded in 1994 and contains 460 member organizations. W3C is the primary web standards organization. They develop the specifications for HTML5, CSS, XML, SVG, and quite a few other technologies. Interoperability is their game, and they’ve been at it for a long time. ActivityPub is one of their standards. It’s a decentralized social media platform. If you’ve heard of Mastodon, you’ve heard of just one of the many things that use ActivityPub. Prospective users of ActivityPub will find a server they like and sign up to that server. There are a bunch of servers running ActivityPub, which all communicate with each other. The interesting thing about ActivityPub is the different apps built on top of it. Lemmy is similar to reddit, Mastodon is similar to twitter, PeerTube is similar to youtube, and Pixelfed is similar to instagram. Despite how different all of these apps are, they can interact with full compatibility using ActivityPub. So, using an account hosted on a server running Mastodon, you could comment on a video from a server running PeerTube, or any other service using ActivityPub. To use the common analogy, “it’s like commenting on a youtube video using your twitter account”. Ideally, the network is supposed to be better than a central network like twitter, because if one server goes down, you can simply create a new account on a different server. Servers can also block other servers that they deem harmful or annoying as a moderation tool. Each server has their own blocklist, although the drama around this can get somewhat petty, or so I’ve heard. An interesting factor of ActivityPub is how corporations interact with it. Instagram Threads began testing its ActivityPub implementation in 2023, and the web creation tool Wordpress is integrated with ActivityPub through an official plugin. Tumblr, the semi-relevant social media site, which is owned by the same people as Wordpress, is also planning to roll out ActivityPub compatibility.[1] The future seems bright for ActivityPub, but what’s that on the horizon?
BlueSky is the creator of the AT, or authenticated transfer protocol. They are a competitor with ActivityPub in the decentralized social media space. BlueSky’s history is suspicious to say the least. The project was announced in 2019 by then twitter CEO Jack Dorsey, and formally incorporated in 2021 as an entirely separate corporation from Twitter. However, BlueSky still has close ties to Twitter that make me hesitant to trust it. Regarding where the funding for BlueSky would be coming from after Twitter's acquisition, Jack Dorsey tweeted “Yes. Twitter doesn’t own it. So a new owner of Twitter wouldn’t matter for some time. Funding would need to be reassessed.”[2] Now, BlueSky is an interesting type of corporation called a public benefit corporation, or PBC. More specifically, BlueSky is a PBLLC. Generally, PBLLCs need to publish benefit reports to the public, as well as annual entity reports. But BlueSky isn’t a general PBLLC. It’s based in Delaware, and PBLLCs in Delaware don’t have to publish their benefit reports to the public. This is somewhat suspicious. Regarding the technology of the AT protocol, it is decentralized like ActivityPub, however, unlike ActivityPub, there are not any different implementations built upon the AT standard yet. There is only the Twitter-esque interface. When the BlueSky project began, it was supposed to be developing a protocol to work with Twitter. Now, it is an orphan, onlooking a drastically changed Twitter.
The central question I was pondering when writing this post was if you could trust BlueSky or not. When I set out to write this, I thought the answer would be obvious. However, the truth doesn’t seem so clearcut. A few months after Twitter's acquisition, Jack Dorsey tweeted that “The biggest issue and my biggest regret is that it became a company.” He says that he would rather Twitter be “A protocol. Def can’t be owned by a state, or company. Becomes clearer every day.”[3]
These quotes from Jack frame the AT protocol as a way of making up for mistakes he made while creating Twitter, however, they could be fabrications meant to present him in a better light. It is unclear if when BlueSky was envisioned, it was meant to be a route to redemption, or a way to preempt an exodus to ActivityPub. Given all the evidence, I am hesitant to make a decisive call. The readers of this post should draw their own conclusions.
I made these two buttons after writing this article. Feel free to use them.
