I'll post this as a top level comment, because I think it is crucial: A few people are saying that it is expensive to run a relay but others have done it for as low as $34/month [1]. So unless somebody presents other proof that it is expensive I would say that those posters are either wrong and trying to mislead us on purpose.
Edit: actually the article links to somebody doing it for $18/month.
I've also done a full network replica (all the data indexed in a postgres) on a raspberry pi (with an 8tb nvme attached via a hat). Its really not expensive to do . And if I wanted to drop data older than say 3 months, it would be even cheaper still.
Case in point! This is an often mentioned statement on which the argument that "atproto is no decentralized" largely hinges. There are honest atproto digs out there but that is not one.
Crucially, the purpose of Blacksky is to provide a service for the (US) black community which has its own moderation decisions while being substantially interoperable.
(Remember, the reasons people use one social network rather than another are almost always social first and technical second, where the social functions are enabled or hindered by the technology)
That post isn't very clear about what specifically happened on BlueSky that made the author move, and I can't see the full thread he links without having a BlackSky account.
What moderation decisions were made regarding this "Link" user that were suspect, using the post author's word?
My perspective of that situation is Link was a fairly popular poster, and had a post that was a quote post of someone from the Bluesky team with an image of an assassinated figure and an alt text that couldve been perceived as a threat to the bluesky team.
> Crucially, the purpose of Blacksky is to provide a service for the (US) black community which has its own moderation decisions while being substantially interoperable.
What are the differences between Bluesky and Blacksky? What does it mean to provide different services for the black community?
> The main Blacksky feed and platform are exclusively for Black people. Non-Black people cannot create accounts to post on Blacksky.
Fascinating
edit: before people take it the wrong way, I mean it's fascinating in that I've never seen these type of moderation policies before. I've seen plenty of communities about cultures (i.e. Ukrainian discord servers), but not around Race and not exclusionary to outsiders. I'm not making a moral judgement here.
Yeah it's worth noting that blacksky provides accounts to non-black users but their posts don't get included in the blacksky feed. And non-blacksky PDS users who are confirmed black still are allowed to be included in the blacksky feed.
So it's multiple components really.
- The blacksky feed which is a curated feed and community built around the US black community on atproto.
- The blacksky client, appview, moderation team, and relay which provide the necessary infrastructure for blacksky to operate independent of the rest of the ecosystem if they need to and for them to tailor their experience to their community.
- The blacksky PDS which serves as a source of truth for data storage and auth for blacksky users that choose to use it.
And of course non-black users can use all of this infrastructure but if you aren't black and you want to host your account on a blacksky PDS you have to pay a small subscription/donation.
It's all for their community but they are more than willing to let other people use their infra as long as those people pay their fair share.
Note that I'm not a blacksky member, just someone involved in the greater atproto space so my understanding of the process is likely not perfect.
But AFAIK the way blacksky operates is that they assume good faith when new users join. If it becomes obvious that you are not black then you will likely get reported or directly hit by moderation action and they will ask you to verify your identity at some level.
I think it's something along the lines of "send a photograph that would be non-trivial to fake". Not necessarily forcing you to dox yourself but requiring that you provide some level of evidence that's visibly resistant to AI/tampering. Now I have no idea the extent to which they do this to be entirely honest but I do know they don't mess around with people doing "digital blackface".
I'm not sure how well that moderation approach will scale at large but given they are a community that has carved out their own niche and not a corp just blindly driving to scale, I doubt they'll see the strain that the greater bluesky and atproto have experienced with moderation struggles at scale. And given all decisions around policy and moderation rules are decided by the Blacksky People's Assembly, as the community evolves participants can participate in governance and help craft the process if they are dissatisfied.
i.e. it becomes clear you are using it as a sockpuppet account (some users have been caught trying to do this), outright saying you aren't black, etc.
Like if you aren't being a niche internet celebrity and aren't trying to play main character on the internet it's unlikely you'd get caught unless you were particularly stupid but that's also kinda part of the point. It's a community and people in that community know each other both online and IRL. It'd be pretty hard to be involved in the community without leaving behind an evidence trail of you blatantly lying about who you are.
Go into the subreddit "blackpeopletwitter" and just open a bunch of threads and look for someone commenting "found the white guy", or something like that.
Not that that isn’t a practical concern, but that’s not the level at which the network claims to be decentralized. Your account was banned by one participant in the hypothetical decentralized network.
Agreed, in theory all participants are equal and being banned by one participant shouldn't lock you out of a decentralized network.
In practice, the vast majority of handles (98.9% as of 2024) are under bsky.social [1]. Yes, alternative PDS providers exist, but if the default onboarding funnels everyone into one provider, and the average user doesn't even know what a PDS is, then decentralization is an implementation detail, not a user-facing reality.
That's just the bluesky PBLLC PDS that banned you or refused to register you.
You can create an account with any email address you want if you host your own PDS or you can find another PDS that someone else hosts that is willing to register you an account.
One participant's new account spam protection has nothing to do with the network at large being centralised
Only if you choose to use bluesky PBLLC's relays and it's super trivial to not do that. Plus you can run your own relay super cheaply.
Side note: it hasn't been called BGS for a very long time. Nowadays they are just called relays and since sync 1.1 the cost for running a relay decreased by multiple orders of magnitude.
If you wish to avoid downvotes you might benefit from stating why you think ActivityPub’s decentralization is superior. We’re in a thread discussing an example of Bluesky decentralization so it’s clearly possible.
There's no other network where anything like this is remotely even possible today, much less at such tiny costs! And it turns out it's actually computationally not hard to do so much stuff!
Imo a good time to remember the old chant: "the only war that matters is the war against imagination; all other wars are subsumed by this war." A lot of totally closed people around HN parts. Atproto is one of the new favs for the shallow hate-brigade (alongside systemd, Linux audio, k8s).
Bluesky's end user story is extremely solid. User-driven, first class moderation tooling, inside the protocol. Why do you think the difference in resources required between the two is decisive?
Your opinion sounds too strongly held to be defended this half-heartedly.
It's more the parts they didn't make federated that hold it back in this regard.
Maybe it's good for end users but that doesn't mean much if it can fall into the same enshittification trap as the others. Also, centralised moderation. I don't want to be dependent on an American company's moderation rules.
There was an article here recently about someone who really tried setting up their own including a did:web and they ran into many problems. https://notes.nora.codes/atproto-again/
There's still many little centralised ties in bluesky and I doubt they'll ever relinquish control completely.
Personally I like nostr a lot more, it seems to be more censorship-resistant and really decentralised.
It was not designed so anyone could run their own social media for $5. It simply has a fundamentally different design that tries to solve different problems.
No need to call it a "joke." Both solutions can co-exist on vastness of the Internet.
ActivityPub is a terrible protocol. The protocol isn't what the specs are, and there's not even a consensus de-facto spec beyond "what Mastodon does". Atproto is a bit better.
Atproto is terrible at decentralization however, because of the model where data is stored decentrally, but accessed centrally, in big servers that need to be aware of all the data. In the ActivityPub model there isn't such a thing as "all the data" - you see what you see.
I am proud of my data, in its many media-type/lexicon feeds (browse my PDS directly at https://pdsls.dev/at://did:plc:zjbq26wybii5ojoypkso2mso), and I want people to know. I put my data on my PDS because it's good data and I believe that people contributing their "data" (sharing the world as they see it) is a democratic / open society virtue that makes the world better.
When you can meaningfully index all the data on a rpi4, I think that's awesome. That makes a lot of people scared or mad, it evokes many of the things people don't like. But it also stems from only ever having seen or known that situation when the entire stack is under corporate control and when it's a mega-corp harvesting the data. From being in captivity. Not when it's one dude bad-example.com running a link indexer for the entire site on an rpi4, and you can too. We don't know what's that like: it's never been possible. https://constellation.microcosm.blue/
There are legit reasons to have Fear Uncertainty and Doubt about atproto, and you don't have to have fun online. You are free to fuck off to less connected less online spaces if that's your bag. But I grew up wanting to be online and i still want to be online, and no service has ever actually done that before, not like this. This is dozens of times better than the next best thing as a distributed connected online system that I can be online with and that gives me the most freedom to build and use interesting neat new mini apps and tools, to be online with.
To say that like it's a bad thing, is, to me, a joke. I acknowledge your values differ, and respect your decision, but it seems so weird to not want to have fun being online, to get better at it, to make more nodes on the noospheric graph, and to made more edges between them. That still feels like the right choice for me, and it's never been tried socially, and I think it has potential to let humanity keep improving in radical ways. In contrast, renouncing the connected feels like a bad dumb move. But enjoy!! GL;HF.
I'm pretty sure the previous poster was not referring to the fact a PDS holds all of YOUR data -- mastodon servers do the very same thing.
I think they might've been referring to the fact that ATProto requires the existence of big, central relay/BGS servers, which are forced to index all the data of everyone on the network for the whole "social" aspect to work well.
That requirement makes hosting a complete, independent ATProto stack much more expensive and resource intensive than hosting an ActivityPub server, thus making ATProto harder to like, actually decentralize. (Correct me if I'm wrong, but I think currently the only independent, full-network relay is the corporate Bluesky one?)
To conflate having doubts about ATProto's design with "not liking fun" feels silly to me; it's a much less battle-tested design, doubts are warranted.
Neither Bluesky, nor other ATProto services require any of this.
RedDwarf is an example of an ATProto client that connects only with your PDS, uses Microcosm (https://www.microcosm.blue/ )'s aggregation index (they calculate aggregate counts for a variety of things with a couple of raspberry pis run off of a home fiber connection): https://reddwarf.app/
No big iron anywhere in the picture.
You give up the ability to search the network, but okay, that's already a feature that all Mastodon users sacrifice as well.
This submission is about BlackSky doing the whole stack themselves. There are other single node app-views. So, thanks for asking, with apologies, let me correct you: you are wrong.
There are lots and lots of full network relays. A couple that run a full network relay on a < $5/mo VPS . See my other comments in this thread, https://news.ycombinator.com/item?id=47302514
If all you want is like and replies (which is the biggest huge part of the app view responsibility), Constellation has done that, is open source, and can do a full network link indexing on a raspberry pi. And which runs public endpoints you can just use, that many apps rely on.
Atproto unlike Mastodon also faces these challenges that, if you tried to do them on Mastodon, would get you screamed at and banned from instances. Fediverse broadly doesn't want you to use "their" data. You can't write search tools. As a result, Mastodon doesn't need anywhere near the complexity, because these unofficial but vociferously enforced terms-of-service disallow thorough interconnection to begin with. Makes it technically much simpler to pull off! No one is allowed to get a full fire hose. No broad app views are allowed. Dunno if this is still true, but for the longest time you wouldn't get likes or comments from someone unless they were already followed by someone on your fedi, and it's a direct result of this deliberate explicit lack of interconnection.
Those constraints greatly reduce the difficulty of scaling Mastodon: technical scaling is not a problem if you socially don't allow scale. So distributed you can't even read it.
Doubt is allowed. But from my view, Mastodon world deserves the doubt. It has stood still, barely budged. I'd love to be wrong. But it seems dominated by the one software that is Mastodon, and it doesn't seem to have a universe of interesting connected neat social softwares sprouting up left and right. The software centralization is near to total, the protocol centralization even worse. As a result, there is little distinguishing interesting novel Mastodon technology happening. The one API is deeply rooted. ActivityPub is trying to find some way to get started breaking this mono-culture & enable innovation but that's just started.
Meanwhile a casual glance at Atproto shows hundreds of amazing apps and systems and clients springing up, from amazing empassioned developers. 2025 saw a massive amount of technical decentralziation. Npmx and Eurosky setting up sizable idependent public/public-ish PDS instances, and has shown people indeed moving their core identity off BlueSky servers at some kind of scale. I forgive you for not knowing how far things have come, and I forget myself how incredibly quickly it's come together. It's still 99.99% Bluesky concentrated hosting, but it is distributed, has independent services for the full network, there is credible exit (1000 moved to npmx hosting in the past ~3 weeks), and to me the most important thing: there is technical diversity & independent exploration. There are so many devs building amazing things. That feels so so so absent on Mastodon.
That's the checkbox at the end of the Fermi great filter of interest for online social systems for me: can we permissionlessly build interesting social systems & experiences with these social protocols, or will each system have to look like a cookie cutter copy of a single instance?
After everything that spawned at the first AtmosphereConf last year, I'm eager to see what happens after the one coming up. We got all this from stuff that started there, or was built on things started there.
I'll post this as a top level comment, because I think it is crucial: A few people are saying that it is expensive to run a relay but others have done it for as low as $34/month [1]. So unless somebody presents other proof that it is expensive I would say that those posters are either wrong and trying to mislead us on purpose.
Edit: actually the article links to somebody doing it for $18/month.
[1] https://whtwnd.com/bnewbold.net/3lo7a2a4qxg2l
I've also done a full network replica (all the data indexed in a postgres) on a raspberry pi (with an 8tb nvme attached via a hat). Its really not expensive to do . And if I wanted to drop data older than say 3 months, it would be even cheaper still.
Case in point! This is an often mentioned statement on which the argument that "atproto is no decentralized" largely hinges. There are honest atproto digs out there but that is not one.
How much was the 8TB NVMe?
Cheaper than it is now! I think it was about $1100 at the time, definitely the most expensive part of the whole setup
Some more background and a user report of the migration process: https://gregpak.net/2025/11/13/how-and-why-i-moved-from-a-bl...
Crucially, the purpose of Blacksky is to provide a service for the (US) black community which has its own moderation decisions while being substantially interoperable.
(Remember, the reasons people use one social network rather than another are almost always social first and technical second, where the social functions are enabled or hindered by the technology)
That post isn't very clear about what specifically happened on BlueSky that made the author move, and I can't see the full thread he links without having a BlackSky account.
What moderation decisions were made regarding this "Link" user that were suspect, using the post author's word?
There are a lot of misunderstandings about what Blacksky is assuming that it's a just a community fork of Bluesky.
The Blacksky team has a much broader vision for which they decided ATProto was the right architecture.
There's a lot more to read about them up on their site: https://blackskyweb.xyz/
My perspective of that situation is Link was a fairly popular poster, and had a post that was a quote post of someone from the Bluesky team with an image of an assassinated figure and an alt text that couldve been perceived as a threat to the bluesky team.
Some commentary ( https://bsky.app/profile/mackuba.eu/post/3m2jtzlznu22o ).
IIRC it came during a week of discourse & tensions around bluesky moderation concerning some controversial writers ( https://bsky.app/profile/jay.bsky.team/post/3m25esnq4t22y )
I share this just to be helpful a tiny bit but theres likely a lot of context missing and different perspectives on this.
> Crucially, the purpose of Blacksky is to provide a service for the (US) black community which has its own moderation decisions while being substantially interoperable.
What are the differences between Bluesky and Blacksky? What does it mean to provide different services for the black community?
https://docs.blacksky.community/list-of-our-services
> The main Blacksky feed and platform are exclusively for Black people. Non-Black people cannot create accounts to post on Blacksky.
Fascinating
edit: before people take it the wrong way, I mean it's fascinating in that I've never seen these type of moderation policies before. I've seen plenty of communities about cultures (i.e. Ukrainian discord servers), but not around Race and not exclusionary to outsiders. I'm not making a moral judgement here.
Yeah it's worth noting that blacksky provides accounts to non-black users but their posts don't get included in the blacksky feed. And non-blacksky PDS users who are confirmed black still are allowed to be included in the blacksky feed.
So it's multiple components really.
- The blacksky feed which is a curated feed and community built around the US black community on atproto.
- The blacksky client, appview, moderation team, and relay which provide the necessary infrastructure for blacksky to operate independent of the rest of the ecosystem if they need to and for them to tailor their experience to their community.
- The blacksky PDS which serves as a source of truth for data storage and auth for blacksky users that choose to use it.
And of course non-black users can use all of this infrastructure but if you aren't black and you want to host your account on a blacksky PDS you have to pay a small subscription/donation.
It's all for their community but they are more than willing to let other people use their infra as long as those people pay their fair share.
Not that I’m going to do it myself, but what’s to stop a non-black person from signing up? Do you verify people’s identities?
I assume it's mostly the same thing that keeps non-Catholics from taking communion at Catholic mass.
Yes, as far as i know it's an honest self-report kind of thing.
tasteless wafers?
Note that I'm not a blacksky member, just someone involved in the greater atproto space so my understanding of the process is likely not perfect.
But AFAIK the way blacksky operates is that they assume good faith when new users join. If it becomes obvious that you are not black then you will likely get reported or directly hit by moderation action and they will ask you to verify your identity at some level.
I think it's something along the lines of "send a photograph that would be non-trivial to fake". Not necessarily forcing you to dox yourself but requiring that you provide some level of evidence that's visibly resistant to AI/tampering. Now I have no idea the extent to which they do this to be entirely honest but I do know they don't mess around with people doing "digital blackface".
I'm not sure how well that moderation approach will scale at large but given they are a community that has carved out their own niche and not a corp just blindly driving to scale, I doubt they'll see the strain that the greater bluesky and atproto have experienced with moderation struggles at scale. And given all decisions around policy and moderation rules are decided by the Blacksky People's Assembly, as the community evolves participants can participate in governance and help craft the process if they are dissatisfied.
What does it mean to be “obviously not black” in a digital context?
i.e. it becomes clear you are using it as a sockpuppet account (some users have been caught trying to do this), outright saying you aren't black, etc.
Like if you aren't being a niche internet celebrity and aren't trying to play main character on the internet it's unlikely you'd get caught unless you were particularly stupid but that's also kinda part of the point. It's a community and people in that community know each other both online and IRL. It'd be pretty hard to be involved in the community without leaving behind an evidence trail of you blatantly lying about who you are.
Go into the subreddit "blackpeopletwitter" and just open a bunch of threads and look for someone commenting "found the white guy", or something like that.
I don't exactly know either, but it's probably some sort of lax verification measure like a selfie.
Don't need extreme measures to keep bad actors out if you're able and willing to throw out anyone who obviously doesn't intend on playing nice.
Some previous Blacksky discussion:
Blacksky grew to millions of users without spending a dollar
https://news.ycombinator.com/item?id=45018773
Is this self imposed segregation?
only if you block them
The "decentralization" of Bluesky is a joke.
Despite its faults ActivityPub is superior.
I lean the same way. I signed up with an alias and got instantly banned.
Their support also drops certain alias emails, so there's no way to appeal.
A "decentralized" network that locks you out for using basic email privacy tooling, with zero recourse, is centralized where it counts.
Not that that isn’t a practical concern, but that’s not the level at which the network claims to be decentralized. Your account was banned by one participant in the hypothetical decentralized network.
Agreed, in theory all participants are equal and being banned by one participant shouldn't lock you out of a decentralized network.
In practice, the vast majority of handles (98.9% as of 2024) are under bsky.social [1]. Yes, alternative PDS providers exist, but if the default onboarding funnels everyone into one provider, and the average user doesn't even know what a PDS is, then decentralization is an implementation detail, not a user-facing reality.
[1]: https://arxiv.org/html/2408.12449
That's just the bluesky PBLLC PDS that banned you or refused to register you.
You can create an account with any email address you want if you host your own PDS or you can find another PDS that someone else hosts that is willing to register you an account.
One participant's new account spam protection has nothing to do with the network at large being centralised
You're still reliant on the centralised bluesky BGS.
Only if you choose to use bluesky PBLLC's relays and it's super trivial to not do that. Plus you can run your own relay super cheaply.
Side note: it hasn't been called BGS for a very long time. Nowadays they are just called relays and since sync 1.1 the cost for running a relay decreased by multiple orders of magnitude.
The cool thing is you can host your own node with its own rules; you should host an anonymous server and you can set the rules.
If you wish to avoid downvotes you might benefit from stating why you think ActivityPub’s decentralization is superior. We’re in a thread discussing an example of Bluesky decentralization so it’s clearly possible.
The amount of resources required to federate with Bluesky (i.e. ingest the entire firehose) is untenable.
Everybody is saying that but that but here is Bryan Newbold running one on $34/month: https://whtwnd.com/bnewbold.net/3lo7a2a4qxg2l
Ingressing the firehose is by far the easiest part. Here's someone doing it on a $4/mo VPS. Lots of other examples, many on slightly more expensive systems. Phil here also runs a public link indexer service for all Bluesky on a raspberry pi 4 ("Constellation")!! https://bsky.app/profile/bad-example.com/post/3mfkrfvy3ok2u https://constellation.microcosm.blue/
There's no other network where anything like this is remotely even possible today, much less at such tiny costs! And it turns out it's actually computationally not hard to do so much stuff!
I ran into this really great thread from Henry Farrell on people who overly polarized themselves, who shut down being willing to hear anything else. https://bsky.app/profile/himself.bsky.social/post/3mgagtkjg7...
Imo a good time to remember the old chant: "the only war that matters is the war against imagination; all other wars are subsumed by this war." A lot of totally closed people around HN parts. Atproto is one of the new favs for the shallow hate-brigade (alongside systemd, Linux audio, k8s).
Bluesky's end user story is extremely solid. User-driven, first class moderation tooling, inside the protocol. Why do you think the difference in resources required between the two is decisive?
Your opinion sounds too strongly held to be defended this half-heartedly.
It's more the parts they didn't make federated that hold it back in this regard.
Maybe it's good for end users but that doesn't mean much if it can fall into the same enshittification trap as the others. Also, centralised moderation. I don't want to be dependent on an American company's moderation rules.
There was an article here recently about someone who really tried setting up their own including a did:web and they ran into many problems. https://notes.nora.codes/atproto-again/
There's still many little centralised ties in bluesky and I doubt they'll ever relinquish control completely.
Personally I like nostr a lot more, it seems to be more censorship-resistant and really decentralised.
It was not designed so anyone could run their own social media for $5. It simply has a fundamentally different design that tries to solve different problems.
No need to call it a "joke." Both solutions can co-exist on vastness of the Internet.
ActivityPub is a terrible protocol. The protocol isn't what the specs are, and there's not even a consensus de-facto spec beyond "what Mastodon does". Atproto is a bit better.
Atproto is terrible at decentralization however, because of the model where data is stored decentrally, but accessed centrally, in big servers that need to be aware of all the data. In the ActivityPub model there isn't such a thing as "all the data" - you see what you see.
That's, like, your opinion, man.
I am proud of my data, in its many media-type/lexicon feeds (browse my PDS directly at https://pdsls.dev/at://did:plc:zjbq26wybii5ojoypkso2mso), and I want people to know. I put my data on my PDS because it's good data and I believe that people contributing their "data" (sharing the world as they see it) is a democratic / open society virtue that makes the world better.
When you can meaningfully index all the data on a rpi4, I think that's awesome. That makes a lot of people scared or mad, it evokes many of the things people don't like. But it also stems from only ever having seen or known that situation when the entire stack is under corporate control and when it's a mega-corp harvesting the data. From being in captivity. Not when it's one dude bad-example.com running a link indexer for the entire site on an rpi4, and you can too. We don't know what's that like: it's never been possible. https://constellation.microcosm.blue/
There are legit reasons to have Fear Uncertainty and Doubt about atproto, and you don't have to have fun online. You are free to fuck off to less connected less online spaces if that's your bag. But I grew up wanting to be online and i still want to be online, and no service has ever actually done that before, not like this. This is dozens of times better than the next best thing as a distributed connected online system that I can be online with and that gives me the most freedom to build and use interesting neat new mini apps and tools, to be online with.
To say that like it's a bad thing, is, to me, a joke. I acknowledge your values differ, and respect your decision, but it seems so weird to not want to have fun being online, to get better at it, to make more nodes on the noospheric graph, and to made more edges between them. That still feels like the right choice for me, and it's never been tried socially, and I think it has potential to let humanity keep improving in radical ways. In contrast, renouncing the connected feels like a bad dumb move. But enjoy!! GL;HF.
I'm pretty sure the previous poster was not referring to the fact a PDS holds all of YOUR data -- mastodon servers do the very same thing.
I think they might've been referring to the fact that ATProto requires the existence of big, central relay/BGS servers, which are forced to index all the data of everyone on the network for the whole "social" aspect to work well.
That requirement makes hosting a complete, independent ATProto stack much more expensive and resource intensive than hosting an ActivityPub server, thus making ATProto harder to like, actually decentralize. (Correct me if I'm wrong, but I think currently the only independent, full-network relay is the corporate Bluesky one?)
To conflate having doubts about ATProto's design with "not liking fun" feels silly to me; it's a much less battle-tested design, doubts are warranted.
This isn't accurate tho.
Neither Bluesky, nor other ATProto services require any of this.
RedDwarf is an example of an ATProto client that connects only with your PDS, uses Microcosm (https://www.microcosm.blue/ )'s aggregation index (they calculate aggregate counts for a variety of things with a couple of raspberry pis run off of a home fiber connection): https://reddwarf.app/
No big iron anywhere in the picture.
You give up the ability to search the network, but okay, that's already a feature that all Mastodon users sacrifice as well.
The "big" central relay servers are not big at all and are actually quiet cheap: https://whtwnd.com/bnewbold.net/3lo7a2a4qxg2l
This submission is about BlackSky doing the whole stack themselves. There are other single node app-views. So, thanks for asking, with apologies, let me correct you: you are wrong.
There are lots and lots of full network relays. A couple that run a full network relay on a < $5/mo VPS . See my other comments in this thread, https://news.ycombinator.com/item?id=47302514
If all you want is like and replies (which is the biggest huge part of the app view responsibility), Constellation has done that, is open source, and can do a full network link indexing on a raspberry pi. And which runs public endpoints you can just use, that many apps rely on.
Atproto unlike Mastodon also faces these challenges that, if you tried to do them on Mastodon, would get you screamed at and banned from instances. Fediverse broadly doesn't want you to use "their" data. You can't write search tools. As a result, Mastodon doesn't need anywhere near the complexity, because these unofficial but vociferously enforced terms-of-service disallow thorough interconnection to begin with. Makes it technically much simpler to pull off! No one is allowed to get a full fire hose. No broad app views are allowed. Dunno if this is still true, but for the longest time you wouldn't get likes or comments from someone unless they were already followed by someone on your fedi, and it's a direct result of this deliberate explicit lack of interconnection.
Those constraints greatly reduce the difficulty of scaling Mastodon: technical scaling is not a problem if you socially don't allow scale. So distributed you can't even read it.
Doubt is allowed. But from my view, Mastodon world deserves the doubt. It has stood still, barely budged. I'd love to be wrong. But it seems dominated by the one software that is Mastodon, and it doesn't seem to have a universe of interesting connected neat social softwares sprouting up left and right. The software centralization is near to total, the protocol centralization even worse. As a result, there is little distinguishing interesting novel Mastodon technology happening. The one API is deeply rooted. ActivityPub is trying to find some way to get started breaking this mono-culture & enable innovation but that's just started.
Meanwhile a casual glance at Atproto shows hundreds of amazing apps and systems and clients springing up, from amazing empassioned developers. 2025 saw a massive amount of technical decentralziation. Npmx and Eurosky setting up sizable idependent public/public-ish PDS instances, and has shown people indeed moving their core identity off BlueSky servers at some kind of scale. I forgive you for not knowing how far things have come, and I forget myself how incredibly quickly it's come together. It's still 99.99% Bluesky concentrated hosting, but it is distributed, has independent services for the full network, there is credible exit (1000 moved to npmx hosting in the past ~3 weeks), and to me the most important thing: there is technical diversity & independent exploration. There are so many devs building amazing things. That feels so so so absent on Mastodon.
That's the checkbox at the end of the Fermi great filter of interest for online social systems for me: can we permissionlessly build interesting social systems & experiences with these social protocols, or will each system have to look like a cookie cutter copy of a single instance?
After everything that spawned at the first AtmosphereConf last year, I'm eager to see what happens after the one coming up. We got all this from stuff that started there, or was built on things started there.