Overview: Bluesky and the ATmosphere

The ATmosphere is the information ecosystem based on ATproto, the protocol developed by and for Bluesky. More interconnected apps are emerging. The potential for better online conversations is profound... if adequate revenue streams can be confirmed.

(last edit: February 2025)

Just as Mastodon is on the Fediverse, an information ecosystem where it and other apps can interact using the ActivityPub protocol, the Bluesky protocol (ATproto) underpins the ATmosphere ecosystem. In 2025, I'm betting that this is the most promising ground for #AI4communities.

Origins: Bluesky

ATproto was originally going to underpin Twitter before Elon Musk bought it. Moreover, when the Bluesky team then spun off from Twitter, they decided to keep many things unchanged, making the transition easier for people fleeing X.

The result looked and felt so similar that many people didn't spot how the open, permissionless nature of this new environment set Bluesky apart. Some key Bluesky features include:

• Custom feeds, each a subset of the Bluesky firehose, tuned to a particular community's interests and moderation preferences, created by anyone using a variety of 3rd party tools (see Bluesky custom feeds) and usable by anyone by simply pinning the feed to their interface
• Labellers apply labels to accounts - like custom feeds, anyone can create one, using a variety of tools, and anyone can subscribe to them if they want to see the label
• Block/mute lists are a sort of labeller: subscribe to one and you'll never see content from anyone on the list in your timeline
• Starter packs package a list of up to 150 people and (optionally) custom feeds relevant to a particular topic, and provide a feed of the people's posts.
• 3rd party apps: you don't need to use the official Bluesky app - there are many others, and because the ATmosphere is permissionless they won't go the way of Tweetdeck.

Enter the ATmosphere

The ATmophere is a permissionless ecosystem - anyone can build anything they like, and can access the Bluesky feed, without having to get Bluesky Social PBC's permission.

So, like Mastodon, Bluesky is not the only kid on its protocol block: in mid-2024 the Whitewind blogging platform launched, and within a few months a plethora of other apps were in beta, including Instagram- & TikTok lookalikes (all tools tagged #atproto and #tool).

Is it decentralised?

Yes, but not as decentralised as Fediverse. The key arguments in this once-fractious debate were both articulated and calmed by two protocol engineers: Christine Lemmer-Webber (ActivityPub co-author) and Bryan Newbold of Bluesky, who exchanged three enormous blog posts. After reading, annotating and generally struggling through all three (and more), I came out with a few conclusions (paraphrased from my newsletter from December 2024 and January 2025):

• There are different degrees of decentralisation, and different ways to get there. A comparison between the relatively mature Fediverse and Bluesky, with its brand-new protocol, is therefore tricky, particularly as Bluesky is focusing first and foremost on providing an X-like experience as possible for everyone fleeing X, which required certain choices to be made.
• There are too many blog posts, not enough wikis - someone should lock these two in a room somewhere until they come up with a text they both agree on
• I hope this protocol competition will evolve until the two spaces complement each other, as:
  • ATProto's shared-heap model structurally favours few servers, "and thus has a natural centralizing force"
  • ActivityPub has an incentive to keep the average followers/user low.
• the Fediverse will therefore probably remain a good place for cozyweb spaces, and co-exist with more global conversations on the more centralised and business-like ATmosphere.
• The world needs both.

What does the ATmosphere represent?

I first saw this when I published my December newsletter, and an extract from it as a stand-alone post, on Whitewind (see everything I Do or Think tagged #Whitewind).

When you sign up to blog on Whitewind, you use your Bluesky ID, and your blog posts live in your Bluesky Personal Data Store. So it's your content, and if Whitewind disappears, you can take it with you to another provider (or build your own), and all of your links keep working. Whitewind doesn't own you. You own you.

Moreover, there's "seamless comments integration with BlueSky: a comment posted to the blog is shared on the commenter's Bluesky account, and whenever someone shares the post on Bluesky it also appears under the post" - Thinking transparently in the ATmosphere.

The code for that integration is freely available, so this has massive implications for website-based communities, among other things.

One of those other things is #ai4communities, which was originally more Fediverse-oriented when I first started articulating it in January 2023. In 2024 I began revisiting it on my experimental wiki with a "technology-agnostic" post accompanied by sub-pages exploring how it would look on the Fediverse, the ATmosphere and (tbd) Nostr. The exercise convinced me that the ATmosphere is most promising, which is why it's been the focus of recent newsletters.