In January 2025, I became aware that there was a real problem with Pixelfed, the "Instagram inspired Fediverse client". The problem is
IS PIXELFED SAWING OFF THE BRANCH THAT THE FEDIVERSE IS SITTING ON? by Ploum on 2025-12-04 https://ploum.net/2025-12-04-pixelfed-against-fediverse.html threatening the whole Fediverse. As Pixelfed received a lot of media attention, I choose to wait. In March 2025, I decided that the situation was quieter and wrote an email to Dansup, Pixelfed’s maintainer, with an early draft of this post. Dan’s promptly replied, in a friendly tone. But didn’t want to acknowledge the problem which I’ve confirmed many times with Pixelfed users. I want to bring the debate on the public place. If I’m wrong, I will at least understand why. If Dan is wrong on this very specific issue, we will at least open the debate. This post will be shared to my Fediverse audience through my @ploum@mamot.fr Mastodon account. But Pixelfed users will not see it. Even if they follow me, even if many people they follow boost it. Instead, they will see a picture of my broken keyboard that I posted a week ago. The latest post of Ploum according to Pixelfed. https://ploum.net/files/pixelfedploum.png Ploum’s real Fediverse timeline (mamot.fr) https://mamot.fr/@ploum That’s because, despite its name, Pixelfed is NOT a true Fediverse application. It does NOT respect the ActivityPub protocol. Any Pixelfed user following my @ploum@mamot.fr will only see a very small fraction of what I post. They may not see anything from me for months. But why? Simple! The Pixelfed app has unilaterally decided not to display most Fediverse posts for the arbitrary reason that they do not contain a picture. This is done on purpose and by design. Pixelfed is designed to mimic Instagram. Displaying text without pictures was deliberately removed from the code (it was possible in previous versions) in order to make the interface prettier. This is unlike a previous problem where Pixelfed would allow unauthorised users to read private posts from unknowing fediverse users, which was promptly fixed. Pixelfed leaks private posts from other Fediverse instances (fokus.cool) https://fokus.cool/2025/03/25/pixelfed-vulnerability.html In this case, we are dealing with a conscious design decision by the developers. Being pretty is more important than transmitting messages. Technically, this means that a Pixelfed user P will think that he follows someone but will miss most of the content. On the opposite, the sender, for example a Mastodon user M, will believe that P has received his message because M follows him. This is a grave abuse of the protocol: messages are silently dropped. It stands against everything the Fediverse is trying to do: allow users to communicate. My experience with open protocols allows me to say that it is a critical problem and that it cannot be tolerated. Would you settle for a mail provider which silently drop all emails you receive if they contain the letter "P"? The principle behind a communication protocol is to create trust that messages are transmitted. Those messages could, of course, be filtered by the users but those filters should be manually triggered and always removable. If a message is not delivered, the sender should be notified. In 2025, I’ve read several articles about people trying the Fediverse but leaving it because "there’s not enough content despites following lot of people". Due to the Pixelfed buzz in January, I’m now wondering: "how many of those people were using Pixelfed and effectively missing most of the Fediverse content?" The importance of respecting the protocol ========================================= I cannot stress enough how important that problem is. If Pixelfed becomes a significant actor, its position will gravely undermine the ActivityPub protocol to the point of making it meaningless. Imagine a new client, TextFed, that will never display posts with pictures. That makes as much sense as the opposite. Lots of people, like me, find pictures disturbing and some people cannot see pictures at all. So TextFed makes as much sense as Pixelfed. Once you have TextFed, you realise that TextFed and PixelFed users can follow each other, they can comment on post from Mastodon users, they can exchange private messages but they will never be able to see post from each other. For any normal users, there’s no real way to understand that they miss some messages. And even if you do, it is very hard to find that the cause is the absence of pictures in them make them "not pretty enough" to Pixelfed developers. Worse of all : some Mastodon posts do contain a picture but are not displayed in Pixelfed. That’s because the picture is from a link preview and was not manually uploaded. Try to explain that to your friends that reluctantly followed you on the Fediverse. Have a look at any Mastodon account and try to guess which posts will we showed to the Pixelfed followers! That’s not something any normal human is supposed to understand. For Pixelfed users, there’s no way to see they are missing on some content. For Mastodon users, there’s no way to see that some of their audience is missing on some content. With the trust in the protocol broken, people will revert to create Mastodon accounts to follow Mastodon, Pixelfed accounts to follow Pixelfed and Textfed to follow Textfed. Even if it is not 100% needed, that’s the first intuition. It’s already happening around me: I’ve witnessed multiple people with a Mastodon account creating a Pixelfed account to follow Pixelfed users. They do this naturally because they were used to do that with Twitter and Instagram. Congratulations, you have successfully broken ActivityPub and, as a result, the whole Fediverse. What Meta was not able to do with Threads, the Fediverse did it to itself. Because it was prettier. How to Kill a Decentralised Network (such as the Fediverse) (ploum.net) https://ploum.net/2023-06-23-how-to-kill-decentralised-networks.html Pixelfed will be forced to comply anyway ======================================== Now, imagine for a moment that Pixelfed takes off (which is something I wish for and would be healthy for the Fediverse) and that interactions are strong between Mastodon users and Pixelfed users (also something I wish for). I let you imagine how many bug reports developers will receive about "some posts are not appearing in my followers timeline" or "not appearing in my timeline". This will result in a heavy pressure for Pixelfed devs to implement text-only messages. They will, at some point, be forced to comply, having eroded trust in the Fediverse for nothing. Once a major actor in a decentralised network starts to mess with the protocol, there are only two possible output: either that actor lose steam or that actor becomes dominant enough to impose its own vision of the protocol. In fact, there’s a third option: the whole protocol becomes irrelevant because nobody trust it anymore. What if Pixelfed becomes dominant? ================================== But imagine that Pixelfed is now so important that they can stick to their guns and refuse to display text messages. Well, there’s a simple answer: every other fediverse software will now add an image with every post. Mastodon will probably gain a configurable "default picture to attach to every post so your posts are displayed in Pixelfed". And now, without having formerly formalised it, the ActivityPub protocol requires every message to have a picture. That’s how protocol works. It already happened: that’s how all mail clients started to implement the winmail.dat bug. The Winmail.dat Syndrome (ploum.net) https://ploum.net/winmail-dat-syndrome/index.html Sysadmins handling storage and bandwidth for the Fediverse thank you in advance. We are not there yet ==================== Fortunately, we are not there yet. Pixelfed is still brand new. It still can go back to displaying every message an end user expect to see when following another Fediverse user. I stress out that it should be by default, not a hidden setting. Nearly all Pixelfed users I’ve asked were unaware of that problem. They thought that if they follow someone on the Fediverse, they should, by default, see all their public posts. There’s no negotiation. No warning on the Pixelfed website will be enough. In a federated communication system, filters should be opt-in. If fact, that’s what older versions of Pixelfed were doing. But, while text messages MUST be displayed by default (MUST as in RFC), they can still me displayed as less important. For example, one could imagine having them smaller or whatever you find pretty as long as it is clear that the message is there. I trust Pixelfed devs to be creative here. The Fediverse is growing. The Fediverse is working well. The Fediverse is a tool that we urgently ned in those trying times. Let’s not saw off the branch on which we stand when we need it the most. Illustration by David Revoy, CC-By-SA https://www.peppercarrot.com/en/viewer/misc__2024-09-09_My-Neighboor-Mastodo...