Free Mastodon in the free Fediverse

Fediverse are internet services composed of small and independent websites that automatically share content among themselves, forming a large decentralized network. One of them is the social network Mastodon. They mostly operate on the principle of open-source software published under some free licenses. Let us recall that, unlike proprietary licenses, these ensure that anyone can freely copy, use, improve, and distribute the software, but must retain the license, thus allowing others to do the same.

As a niche for those who want to be outside the power of platforms owned and influenced by the world's wealthiest, Mastodon is definitely viable.

The most famous example of free software is the Linux operating system, the Firefox browser, the VLC media player, the WordPress content management system, or the Signal messenger. And, ultimately, the vast majority of code powering the daily functioning of the entire internet. Development is sometimes supported by specialized foundations, but often it is in the hands of enthusiastic volunteers programming in their free time. The resulting program then belongs to everyone – it’s no wonder that the roots of the free software movement lie in the libre-minded 1960s and seventies in the USA.

The service from the world of Fediverse – for example, image sharing Pixelfed, video service PeerTube, or social network Mastodon – can be operated by anyone who can handle the technical aspects. Individual “instances,” i.e., specific servers of such services, are managed and run by their respective operators, who are often foundations, academic institutions, non-profits, communities, groups of tech enthusiasts, companies, or individuals.

An example is the PeerTube service, which, like YouTube, allows uploading and watching videos. For sharing, it uses a principle similar to torrents, where videos are ideally sent directly between the computers of viewers. A Czech PeerTube instance is for example the server vhsky.cz, operated by a few tech enthusiasts from their own pockets, which allows anyone to share their videos. The Polish municipality of Stary Sącz also to PeerTube to eliminate dependence on YouTube for their video channel.

The dependence on platform operators can be problematic even in crisis communication, for example during floods, when the dissemination of important messages is entirely at the mercy of the operators. It can happen that warnings about a flood wave or fire are removed by a hired moderator somewhere in an open space in Asia as spam, as happened during the Czech floods in 2024 or wildfires in California.

Even audio podcasters no longer have to depend on Spotify’s discretion or other corporate networks and can try Fediverse platforms like Funkwhale, Owncast, or Castopod, although the audience is still sparse.

Individual instances “federate” with each other, exchanging content, so a user of one can follow and share posts from users on all other instances. The network thus becomes decentralized: no one manages it centrally, nor does it have a “central point” that could be regulated, attacked, banned, or manipulated unilaterally. And it has no owner. Specific rules are set and posts moderated by the administrators of individual nodes, and if they no longer suit you (or you no longer suit them), you can switch elsewhere.

Mastodon and the exodus from Twitter

In the fall of 2016, twenty-three-year-old Eugen Rochko launched the social network Mastodon, which he began programming based on Fediverse principles while still a student at the University of Jena. Initially, it was a technological toy, a hobby in programming discussion forums he was running at the time. Rochko was already tired of moving from one messenger to another or from one social network to another as they emerged, gained popularity, and then disappeared. “How many more times do I have to do this?! We need something that will work forever,” he said at the time. He considered that it didn’t make sense for services not to be able to communicate with each other, and built the network on the principle of federation.

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Many communication apps and social networks are emerging, some of which offer great features in privacy and encryption, but the usual problem is how to persuade users to use a network where they have no one to talk to. This is called the “network effect”: the usefulness of a network for users increases significantly with the number of users already using it. When the network size exceeds a “critical mass,” it will grow on its own. Mastodon virally gained popularity among tech enthusiasts for its openness and decentralization, but the rapid rise came only at the end of 2022.

Elon Musk then bought Twitter for 44 billion dollars, and his first steps already led to the departure of some management, hundreds of employees, and frightened users. It took little to block accounts of journalists.

About nineteen-year-old Jack Sweeney wrote a bot that extracted the location of Elon Musk’s private jet from public flight records (used by, for example, the well-known flightradar24.com or better ADSBexchange.com) and published it on the Twitter account ElonJet (after the Russian invasion of Ukraine, he also started publishing the movements of Russian oligarchs’ jets). Musk initially offered Sweeney 5000 dollars to delete the account. But when he finally bought the entire social network, he canceled it himself.

In the tense atmosphere around the sale of Twitter and examining what will happen with Musk’s declared freedom of speech, journalists started paying attention to the story. And the enraged Musk immediately blocked the accounts of journalists from respected media such as The Intercept, New York Times, CNN, Washington Post, or Voice of America, who wrote about the case. And despite declaring “amnesty” for previously banned accounts spreading hate, neo-Nazism, or racial superiority, in the name of free speech, he reinstated them.

The exodus of users frightened by the new owner was directed precisely to Mastodon, which was gaining tens and later hundreds of thousands of new users daily. Musk’s Twitter, in a panic, began labeling links to alternative social networks as dangerous, as if it were malware – this drew media attention and a wave of refugees, boosting Mastodon’s popularity again. Within a few weeks, its user count climbed to 2.5 million.

Similar waves of exodus have always followed worsening situations elsewhere, such as when the Chinese central government tightened censorship on the social network TikTok.

The success of the social network also attracted investor interest. Rochko, however, rejected all investments with the words that once they have his money, they will want something in return. Mastodon was transformed into a non-profit and is funded by donations and contributions for software development, most of which is still carried out by a large group of volunteers.

The first wave of user influx has subsided (Zuckerberg’s Meta used the exodus from Twitter to launch its competing social network Threads), and the number of users gradually declined again, often discouraged by less intuitive user interfaces. Still, worldwide, its nearly 8,000 instances are used monthly by about 700,000 users.

It has been especially adopted by groups that appreciate its principled openness. Besides prudent tech enthusiasts around open software, it is also a strong left-wing scene.

Surprisingly, it has also become a domain of the LGBTQ+ community. Perhaps partly because the main author of the ActivityPub protocol, which services in the Fediverse exchange messages through, is a trans woman Christine Lemmer-Webber – and the protocol to preserve privacy and sensitivity to users’ specific needs. The current politicization of the topic and the connection of social network owners with transphobic Trump have given the community a reason to choose the platform. And a visitor at one of the last CCC hacker congresses in Hamburg, Germany, might have been surprised how many of the tens of thousands of hackers from around the world dressed in skirts, rainbow ribbons… Or at least cat ears.

A social network in the hands of people

Mastodon does not use any filtering or recommendation algorithms, so users compare it more to gardening: people you follow must choose themselves. And once in a while, they need to prune their garden and weed out the unwanted. Fortunately, Mastodon does not threaten with the term “friend,” and unfollowing someone is not an emotional act of “we are no longer friends,” but merely a technical action (or feedback on feed quality). The advantage is that we set the information flow ourselves, and it’s not done by an opaque algorithm. The disadvantage is less convenience and more work, which is the price for it.

The principle of decentralization resembles email: an account on Mastodon might be called @klokanek@witter.cz, where the first part is the username, and after the second “@” is the name of the specific server. And although many regulations (e.g., the Digital Services Act of the European Union) target centralized social networks, email, due to its decentralized nature, has never been seriously regulated.

Anyone who doesn’t want to do any work can use one of the large instances (like the flagship Mastodon.social), or an organization or group that wants full moderation control can create their own instance (like Czech Radio, European Commission, or Czech Pirate Party), smaller communities run their own instances (in Czechia, for example, the association witter.cz or NoLog.cz, which in 2023 received the Big Brother Positive Award for making privacy-protecting technologies accessible), or even individuals. Running servers costs money; some instances are paid for by their operators out of pocket, others are funded by their users (sometimes registration is by invitation only) – and the model still works. Even without ads, mining, or selling personal data and corporate backing.

Since Mastodon does not need to gather users for its financial model, posts (unless users have explicitly prohibited it) are public and accessible from outside without registration. This eliminates annoying blackmail like “we will show you this post only if you also create an account on Facebook” – and the subsequent collection, analysis, or sale of personal data.

When Donald Trump, supported by Musk, won the US presidential election two years ago, another wave of Twitter/X refugees flooded to the new social network Bluesky, which grew by hundreds of percent within a few days. It is backed by former Twitter employees, where the network was created as an experiment under the original leadership, inspired by Mike Masnick’s essay Protocols, not Platforms: A Technological Approach to Free Speech.

Launching your own Bluesky server is possible but many times more than Mastodon. Moreover, the fundamental weakness remains the same as with other networks owned by someone: investors have put money in and will have interests, at least in monetization. The vulnerability of such centralized ownership was already demonstrated in April 2025, when during opposition protests in Turkey, Bluesky complied with a court order and blocked 72 accounts linked to the opposition ( from Human Rights Watch also addressed to owners of X, YouTube, TikTok, and Facebook, which also succumbed to Turkish government pressure).

Thanks to federation from Mastodon, “bridges” lead to other social networks, so Mastodon users can follow posts from the more open Bluesky (via bridge, for example, in the form of @denikalarm.bsky.social@bsky.brid.gy) or even from Twitter/X (via bridge @jmenouctu@bird.makeup – but for example, the main Mastodon.social instance does not federate posts from X).

Offshoots

After Trump was elected US president in 2016, a wave of LGBTQ+ users and developers fleeing from Twitter arrived on Mastodon. Soon they began complaining about how Eugen Rochko leads the software development and that some features could contribute to disadvantaging certain groups of people. In the open-source world, anyone who knows how can modify the software by adding features or making changes. But these changes must be approved by the main administrator. Rochko did not accept some modifications from new volunteers, and the community complained.

But open software has long had a functioning mechanism called “fork,” which a beekeeper might call a “branch.” Anyone has the right to “split off” their own version of the software and maintain it independently, build their own community, modify its functions, or add any features. They can then offer changes to the original program, take functions from it, or both paths can go separately. As long as they communicate using the same protocol, they speak the same language and can exchange messages.

The freedom of code is so radical that “anyone” can even be a team like Donald Trump’s, which after his account was banned on Twitter, created its own social network Truth Social. It copied and modified Mastodon to suit its needs and even claimed the software as its own, but in violation of the open license, it did not provide the source code, which would allow others to freely use it. Rochko formally on it with a letter, and the organization Software Freedom Conservancy filed a legal objection, after which the source code quietly appeared.

Defederation

That freedom of expression does not mean eliminating moderation was realized by Mastodon quite early.

On Saturday, October 27, 2018, during morning prayer, a man entered the Pittsburgh synagogue and shot and killed 11 people and wounded six others. When it was revealed that the man published his anti-Semitic comments on the far-right network Gab, where his profile motto was “Jews are Satan’s children” and no one stopped his posts, tech companies began cancelling services – the hosting provider shut down servers, the registrar disabled the domain, and payment companies stopped processing user payments.

To bypass the ban on its mobile apps in Apple and Google stores, Gab switched to Mastodon software in 2019 – and its users started using official Mastodon apps. Suddenly, the racist network with a million users became the largest instance of a network previously more left-leaning and anti-racist. “Mastodon was originally developed by a person of Jewish roots from the first generation of immigrants, and its users are often people from marginalized communities,” stated Rochko. “We oppose Gab’s philosophy, which justifies its racist and dehumanizing content with an absolute notion of free speech,” he wrote, adding that the open license allows anyone to use his work, and he cannot force anyone not to federate with Gab, but his own instance Mastodon.social has started blocking Gab. In a rapid wave, Gab was defederated by almost all other instances, and it later turned off its sharing via the ActivityPub protocol itself.

The decentralization principle does not eliminate moderation dilemmas. It begins with spam and malicious bots, which no one wants. But the moderator of each instance is still faced with many questions that large platforms have long encountered. Different countries have different boundaries of free speech: should we delete all potentially illegal expressions, or wait for a court order? And what if Turks object? Should we delete all hate speech and calls for violence, or leave disinformation to flourish? Should we fact-check? But what is a fact and what is just a controversial opinion? Should we federate with instances where rules are more lenient, or where moderation is less strict? And what about those that do not fit our worldview?

Defederation can sometimes lead administrators to mob behavior. The Raspberry Pi foundation, which produces the same-named microcomputer about the size of a cigarette pack, popular among hackers and tinkerers, experienced this. When they announced hiring Toby Roberts, a former police officer who had developed various hidden surveillance and eavesdropping devices for the British police, angry comments started pouring in from the developer community. The moderators responded in a similarly unkind manner and blocked the loudest critics. Soon, the entire instance was under the hashtag #fediblocks, under which administrators share defederation proposals daily. Whether they federate or not is decided individually by each administrator, but this wave of blocking damaged the foundation’s reputation. The lesson most commentators took from the incident is that greater generosity and cooler heads are needed on both sides.

With waves of defederation, it can even happen that the Fediverse fragments into mutually non-communicating islands. It has already happened: extreme right versus the rest of the world. “Gatekeeping,” the decision about which information “goes out,” is shifting from centralized power (now in the hands of oligarchs) to the hands of individual self-governing communities. These become the basic units of the new network. And although moving an individual without social surroundings into a new network is lonely and adventurous, moving a small community is quite feasible.

Freedom is harder

It’s all a bit more complicated than shiny corporate platform clickboxes. That also deters some of the audience, and after waves of refugees from other platforms, there are again declines. Some of it is surely due to user unfamiliarity. Mastodon has already relaxed, and instead of “tooth” (a variant of “tweet”), it simply calls posts “posts.” The star (“favorite”) is a recognition for the author of the post and serves as a bookmark for later. “Boost” (like “retweet”) reposts the post to all your followers. The display of posts can be changed and customized, and you can create lists of users you are especially interested in, or by topics or languages. “Many of the decentralization problems that drove away many users back then have been solved over the last three years,” says a man with the nickname xChaos, who manages the Czech instance f.cz.

It does not have the “stickiness” of recommendation algorithms that aim to create dependency. Sometimes I don’t think about Mastodon for whole weeks, and I don’t miss it, which is a huge relief compared to the relentless checking of social media during a single day with a “fear of missing out” behind my back.

It is held and increasingly used mainly by people for whom principled freedom outweighs the convenience of simplicity: activists of all kinds, hackers, LGBTQ+ community. It’s surprising that, for example, the Czech activist scene clings so much to platforms operated by corporations and is not afraid of their algorithms disadvantaging them in close cooperation with state power. As it is said on Mastodon: “On platforms run by oppressors, you will hardly make a revolution.”

Since Mastodon is not algorithmically distorted, it could behave as a natural, scale-free network, as described by mathematician Albert-László Barabási in his book *Linked*. According to his principle of “preferential attachment,” it would mean that the largest audience would ultimately be those who joined first or stayed the longest.

Mastodon has not become mainstream and probably will not. Czech instances together have about around a thousand users (other Czech users are on foreign instances). But in its ten years of existence, it has proven that as a niche for those who want to be outside the power of platforms owned and influenced by the wealthiest people in the world, it is definitely viable. And if times worsen further, such infrastructure could come in very handy.

The author is a documentary filmmaker. This text is an excerpt from the upcoming Dangerous Books.