Mastodon: the decentralised social network

TL;DR:

• Mastodon is a decentralised, free and ad‑free social network. It operates as a federation of autonomous instances that communicate with each other, giving control back to communities and the people who publish.
• The feed is chronological and not manipulated by engagement algorithms. The result: less noise, fewer toxic posts promoted, and often better mental comfort.
• Privacy: minimal data collection, no advertising profiling. You can choose your instance, migrate elsewhere while keeping your subscriptions, or self‑host.
• Quick comparisons: X is centralised, ad‑driven, algorithmic, with huge reach but more chaos. Mastodon is calmer, community‑oriented, ad‑free with local moderation. Facebook is all‑in‑one and intrusive on data; Mastodon is more sober, focused on public discussion rather than groups/events. Bluesky promises decentralisation but remains fairly centralised, relying on customisable algorithmic feeds; Mastodon is more mature in federation and community culture. Matrix is a complement for decentralised messaging and internal community management; Mastodon is more about public communication.
• X: centralised, ads, algorithms, huge reach but more chaos. Mastodon is calmer, community‑oriented, ad‑free, with local moderation.
• Facebook: all‑in‑one and intrusive on data. Mastodon is more sober, focused on public discussion and not a clone of groups or events.
• Bluesky: promises decentralisation but remains fairly centralised; relies on customisable algorithmic feeds. Mastodon is more mature in federation and community culture.
• Matrix: a complement for decentralised messaging and internal community management. Mastodon serves more for public communication.
• Limitations: less intuitive onboarding, slower discovery of accounts without algorithms, smaller and fragmented audience, distributed moderation that requires choosing the right instances, interoperable ecosystem but sometimes heterogeneous.
• Who it’s for: communities, nonprofits, schools, independent media, collectives and SMEs seeking sovereignty, security and a healthy environment.
• Quick tips: choose an instance aligned with your values, use hashtags and lists to discover, activate content warnings when needed, and combine Mastodon with Matrix for private messaging.

Introduction

Dominant social networks like Facebook or X (formerly Twitter) are controlled by large centralised companies. Their business models rely on data collection and algorithms that maximise user engagement—often at the expense of our well‑being. These platforms decide what we see, exploit our personal information for advertising and can even influence our emotions or opinions. In response, an alternative has gained popularity: Mastodon, a decentralised, free, ad‑free social network designed to give control back to users. Intended both for the general public and for professionals or communities looking for a private, secure and ethical online space, Mastodon promises a different experience—more respectful of personal data and user psychology.

In this article we will explore in depth what Mastodon is and how decentralised social networks work. We will then compare it with X, Facebook, Bluesky and Matrix. Finally, we will discuss the concrete benefits of this approach in terms of privacy, control and mental health while also examining the challenges and limitations to keep in mind.

What is Mastodon?

Screenshot of the Mastodon web interface (version 4.3.1). Each column shows part of the service: on the left, the field to publish a message, then the local, global or list timelines, and notifications.

At first glance, Mastodon’s interface resembles Twitter: there is a feed of short messages (called toots, up to 500 characters) with the ability to reply, boost (retweet) or favourite. However, Mastodon is not a single site owned by a company: it’s a network of interconnected community servers (instances) where users sign up. Each instance is run by an independent person or organisation and sets its own rules, language and theme, yet all can communicate with each other. A user on mastodon.social can thus follow and message a user on piaille.fr or mamot.fr as if they were on the same network. This distributed architecture—known as federation—is at the heart of Mastodon and the entire ‘fediverse’. Mastodon uses an open protocol (ActivityPub), also adopted by other compatible services (e.g., PeerTube for video or Pixelfed for photos), which enables interoperability across platforms.

In practice, Mastodon works like a decentralised Twitter. The project was launched in 2016 by Eugen Rochko, a German developer who wanted to create a community‑funded ‘democratic’ social space without ads or a single owner. Long confined to a circle of enthusiasts (often tech‑savvy supporters of free software), Mastodon really took off at the end of 2022 when Elon Musk’s takeover of Twitter prompted an exodus to this alternative: the service went from about 400,000 to over 1.3 million active users in a few weeks. Since then growth has continued: in December 2024 around 10 million monthly active users were estimated across thousands of instances. That remains modest compared with the giants (Twitter surpassed 300 million before its recent decline), but Mastodon offers a grassroots approach centred on community and transparency.

The principle of decentralisation

Symbolic logo of the Fediverse (community proposal). The five interconnected nodes illustrate a network without a single centre.

Decentralisation means that no central server controls the entire social network. Instead of a single platform like Facebook or Twitter, Mastodon is spread across multiple independent but connected nodes, hence the term federated network.

The diagram above illustrates this idea: each node (coloured point) is connected to all the others, forming a collaborative mesh. In practice this translates into many Mastodon instances that you can freely join. Each instance functions as an autonomous community: it has its own owner/administrator, its own rules of use and local moderation policy. No single entity owns or runs Mastodon as a whole: power is distributed among the volunteer administrators of each server and ultimately among the users themselves.

This architecture brings several notable benefits:

• Individual and community control: Decentralised networks ‘belong to the user community, which decides the uses that may take place there’, notes a report by Renaissance Numérique. Concretely, this means Mastodon users have control over many aspects: choosing a server based on their affinities (you can join a photography‑oriented instance, a general French‑speaking instance, an instance run by and for your organisation, etc.), the ability to change servers if you no longer agree with your community (without losing your subscriptions thanks to account portability), and even the option to create your own Mastodon instance to set your own rules. On a global scale, no authority can arbitrarily impose a policy or censor all users: if a server becomes problematic, others can choose to disconnect it (de‑federate it), but there is no ‘red button’ in the hands of a company or government to shut down Mastodon. Each community is therefore free, within the law, to self‑organise as it sees fit.
• Respect for privacy: On Mastodon, your personal data belongs to you. The platform does not ask you to enter your real name, your phone number or other intrusive information to sign up; a simple email address usually suffices. Because the software is open source and the ecosystem is distributed, there is no centralised advertising profiling or resale of your data to third parties. Mastodon collects and uses only a minimum of data, unlike commercial networks: ‘there is no algorithm and no advertising’, so there is no reason to vacuum up your information for targeting. The official site summarises this philosophy with the slogan ‘The social network that isn’t for sale’: your feed is created and controlled by you, with no ads or forced suggestions; your data and your time remain yours.
• No manipulative algorithm: A key point of Mastodon is the absence of recommendation algorithms in the news feed. Posts from the people you follow appear in pure chronological order, without opaque filtering or insertion of sponsored content or invasive suggestions. You will only see what you deliberately subscribe to. ‘You know better than anyone what you want to see on your main feed. No one wants an algorithm or advertising deciding for us and making us waste our time,’ Mastodon explains on its homepage. This ‘back to basics’ approach gives an increased sense of control: no more endless feeds dictated by AI to capture your attention. On Mastodon, you configure your experience yourself by choosing who to follow and using lists or hashtags to organise content. It may seem confusing when you’re used to being guided by suggestions, but many find it a relief: you regain control over your feed.

In summary, decentralisation offers a more ethical and transparent framework. There is no CEO of Mastodon who can decide a policy change overnight, no shareholders demanding to maximise monetisation at the expense of users. The network belongs to those who bring it to life. Of course, this freedom comes with local responsibilities (each instance admin must maintain their server, enforce its rules, etc.), but for users it translates into an experience that can be shaped in their image within a human‑scale community they can trust.

Benefits for privacy, control and mental health

The Mastodon approach has not only technical or ethical advantages: it can also have a very concrete impact on user well‑being.

As mentioned, centralised networks are often criticised for their detrimental effects on mental health (addiction to infinite scrolling, anxiety fuelled by toxic content, social pressure from ‘likes’, etc.). Mastodon’s design aims to mitigate these problems by changing the rules of the game:

• Less data collection, more privacy: As a non‑profit service, Mastodon has no incentive to spy on your activities. There is no tracking pixel recording your every click, no targeted ads based on your private conversations (in fact, there is no advertising at all on Mastodon). By comparison, scandals like Cambridge Analytica have shown how far Facebook could go in diverting personal data for political or commercial purposes. On Mastodon this risk is greatly reduced: your data is not a commodity. Each instance has its own privacy policy (some record almost nothing apart from public posts), and because they are mostly small, passionate communities rather than multinationals, the temptation to exploit users is much lower. For someone concerned about privacy, Mastodon offers a much less intrusive environment and anonymity by default—you can use a pseudonym and a throwaway email, which is harder on Facebook or Instagram, for example.
• End of the ‘attention economy’: ‘These algorithms exist to maximise engagement… and nothing engages more than controversial, rage‑fuelling content’, notes an observer about mainstream networks. Commercial platforms optimise our feeds to keep us online as long as possible, including by exploiting our negative emotions (anger, fear, jealousy). A recent report described how TikTok’s algorithm exposed vulnerable teenage girls to a spiral of depressive and self‑harm videos, severely worsening their distress. Similarly, a study on Facebook reveals that the network favours anxiety‑inducing content—accidents, illnesses, violence—because it captures the attention of worried people, even at the cost of exacerbating their emotional disorders. This engagement trap is not a bug but a direct consequence of recommendation algorithms optimised for advertising, and it can seriously affect users’ mental health. By eliminating these algorithms, Mastodon breaks the vicious circle. Your feed is no longer manipulated by an AI trying to get a reaction at all costs, but a simple reflection of your chosen subscriptions. You will not suddenly see the latest controversial topic or a shocking video that none of your contacts actually shared. Fewer unwanted solicitations means less digital stress. A French think tank even suggests that tackling the very architecture of recommendations could be a major lever for reducing the harmful effects of networks on society and individuals’ minds. Mastodon offers precisely an experience without automatic recommendations, and many users report that the atmosphere there is calmer.
• Choice of communities and adapted moderation: Another important aspect for well‑being is the quality of the social environment. On large networks we often endure uniform (sometimes lax) moderation rules that can allow toxic behaviour to flourish on a large scale. Mastodon, on the other hand, allows you to choose a community whose rules align with your values. For example, some Mastodon instances strictly prohibit hate speech, harassment or non‑consensual pornography, and their administrators enforce this diligently. If these issues matter to you, joining such an instance guarantees you a healthier feed than, say, global Twitter where violent or extreme content could appear in the trending topics. Since each Mastodon server has its own charter, you can find the place where you feel safe. And if, despite everything, someone bothers you, the classic tools exist (block, mute, report to local moderators). No algorithm will bring trolls to your timeline simply because they generate engagement. Of course this does not mean Mastodon is a perfect world: hateful or unpleasant remarks can appear if you follow the wrong person or if your instance federates with a problematic community. But you have the power to quickly resolve the problem (unsubscribe, ask your admin to block the toxic instance, etc.), whereas on a centralised network you depend on decisions by a remote team that sometimes prioritises free speech at all costs. In short, Mastodon makes it easier to build positive community bubbles—something many people seek for constructive online interactions.
• More human interactions, less chasing likes: On Mastodon, the absence of overly prominent popularity metrics (no public retweet counter, no quote‑tweet button to spread a clash out of context) tends to reduce social pressure and unhealthy virality. Users often describe more measured and authentic exchanges. ‘I’ve made so many friends on Mastodon because I can actually talk to people instead of getting buried by algorithms that reward meaningless numbers over actual interaction,’ says a regular. The focus is on conversation and shared interests rather than performance or buzz. There is no race for followers to become an influencer, since reach remains relative to the modest size of the instance and no global algorithm will randomly catapult content onto everyone’s screens. This digital sobriety can be refreshing and psychologically beneficial: you compare yourself less to others, feel less compulsion to check notifications constantly, and can even forget the network for a few days without fear of missing a major event. In short, Mastodon encourages using social media at your own pace, in a more controlled way—a plus for preserving mental health.

Comparisons with X, Facebook and Bluesky

To better situate Mastodon, let’s examine its differences with three emblematic platforms: X (Twitter), Facebook and Bluesky. Each has its own approach, and Mastodon stands out on several key points:

• X (Twitter): Launched in 2006, Twitter (renamed X in 2023) popularised public microblogging. The main difference is that it is a centralised, commercial platform owned by a company (now Elon Musk). X’s news feed is largely governed by algorithms that highlight tweets based on your past interactions and what generates the most reactions across the network. Advertising is omnipresent and X collects massive amounts of data to refine its targeting. Mastodon, in contrast, has neither ads nor post ranking algorithms. You only see content from accounts you follow, in chronological order. Moderation policies also differ: Twitter applies a single (and sometimes fluctuating) policy to all users with a centralised team, whereas each Mastodon instance has its own rules and moderates its community locally, offering more flexibility. On the other hand, there is no global moderation on Mastodon, so a user banned from one instance can try again on another—requiring collaborative vigilance among admins. As for audience, X still has a huge user base compared with Mastodon. A viral tweet can reach the world in minutes, whereas a Mastodon toot will reach a smaller circle. For brands or personalities, Twitter retains enormous reach that Mastodon does not yet offer. However, X’s virality comes with the chaos we know: rumours going viral, mass harassment, ubiquitous bots and spam. Mastodon avoids much of this through its fragmentation into small communities. It’s a choice between a planetary megaphone (Twitter) and a living‑room discussion (Mastodon), depending on your needs. Note also: X has become a semi‑paid platform (paid verified accounts, advanced features reserved for subscribers), whereas Mastodon is free and will remain so, funded by donations and managed by a non‑profit association.
• Facebook: Mastodon is often compared to Twitter, but what about Facebook? The concept is different (Facebook is based on real profiles, mutual friends and private groups, whereas Mastodon is more oriented toward open posting to strangers, like Twitter). Nevertheless, the centralisation vs decentralisation distinction is similar. Facebook is the archetypal all‑in‑one hegemonic network: all users are on the same platform under the same conditions dictated by Meta. This gives unparalleled power to find anyone easily, but also enormous power to the company over content. Facebook can remove a post or ban an account across the entire network with a click—both reassuring and worrying. Mastodon does not allow a single actor to censor everyone: moderation is distributed; an abusive instance will simply see its members leave. Regarding privacy, Facebook is often criticised for its insatiable appetite for personal data: everything you do is tracked, it even tracks your browsing on other sites via its Like buttons, and has been implicated in dubious data exploitation. Mastodon respects your data: there is no ad tracking or sale of data. Each server hosts its users’ data locally and is responsible for it, but you can move your data to another server if you lose trust. Your Mastodon timeline is smaller, less ‘optimised’, but far more neutral and manageable because there is no algorithm promoting polarising content. Facebook has become a sprawling platform with many services; Mastodon focuses on microblogging and public discussion. It won’t replace everything Facebook does, but for the core of social exchange it fits the bill without the disadvantages of Facebook’s ecosystem. In short, one could say that Mastodon offers a social network where Facebook offers a social ‘society’; the simplicity of Mastodon makes it healthier and less intrusive.
• Bluesky: The newcomer among alternative networks. Created in 2021 by Jack Dorsey, Bluesky aims to develop a new decentralised social network protocol. On paper Bluesky shares a philosophy similar to Mastodon’s—getting away from a single centralised model and giving users control over their data and distribution algorithms. In practice, however, Bluesky is still in closed beta and currently operates quite centrally. Its AT Protocol is open source but developed by a private entity that retains control. At present all Bluesky accounts are hosted on the official server, though it is technically possible to create other servers. The goal is to evolve to a truly federated network where anyone could run their own server, similar to Mastodon. But as of now, Bluesky has a single set of rules for everyone and no server‑level moderation. Moderation is handled centrally by the Bluesky team, contrasting with Mastodon where each server sets its charter and can block others. Bluesky introduces personalised algorithms: by default its feed is chronological, but users can subscribe to alternative feeds or algorithms. Mastodon sticks to a single chronological feed for everyone. Functionally Bluesky is still basic: posts up to 300 characters with images, likes, reposts, replies; no encrypted private messaging, polls or content warnings. Mastodon already offers these features (except end‑to‑end encrypted private messages). Regarding identity, Mastodon uses the @user@server format; Bluesky lets you link your username to a custom domain. Community culture also differs: Bluesky has a relaxed, early‑adopter vibe with lots of memes, while Mastodon has older, diverse communities (developers, journalists, activists) and a culture of mutual aid. Each network attracts different audiences; some people use both for different purposes. Meta’s Threads is also based on ActivityPub but remains centralised on Meta servers.
• Matrix (messaging): Finally, let’s mention Matrix, not a microblogging social network but a decentralised instant messaging protocol often cited in parallel. Matrix is to private/community communication what Mastodon is to public communication. It allows federated chat rooms—your group or company can host a Matrix server (with a client such as Element) for internal exchanges while remaining interoperable with other Matrix servers worldwide. Like Mastodon, Matrix is open source, belongs to no one, and prioritises security (messages can be end‑to‑end encrypted) and data sovereignty. Matrix offers the advantage of not depending on Slack or Discord: you can moderate your own rooms, set your own rules, and no central server can globally censor you. Matrix and Mastodon are therefore complementary: Mastodon for the public news feed and announcements, Matrix for private group chats and real‑time organisation. Many free‑software communities or citizen movements use both: a Mastodon account to communicate outward and build support, and a Matrix space to coordinate members internally in a secure way.

Challenges and limitations of Mastodon

After painting this flattering portrait of Mastodon and the fediverse, we shouldn’t forget that not everything is rosy and that this approach also has challenges to consider. Here are the main limitations or difficulties encountered with Mastodon:

• Onboarding and usability: The user experience on Mastodon can be confusing at first, especially if you come from Facebook or Twitter. Having to choose an instance when signing up is not intuitive for the general public. Even though there is a server guide and generalist instances open to everyone, this choice screen can deter people (‘where are my friends?’, ‘what if I choose the wrong instance?’). Then, once registered, building a network of subscriptions takes effort: by default, your feed is empty since no algorithm suggests popular accounts to follow. You have to search via the search bar or hashtags to discover interesting accounts, which requires more patience and curiosity. This change of habits led many newcomers in 2022 to abandon Mastodon quickly. Mastodon is working to improve onboarding (for example by suggesting accounts to follow), but the experience remains less turnkey than on a centralised network. You need to be willing to learn a bit, which can slow mass adoption. It’s a trade‑off between ease of use and independence: here, independence prevails, at the cost of a slightly longer learning curve.
• Audience size and fragmentation: Mastodon has only a few million active users spread across thousands of servers. This yields smaller, tighter communities but also less content and diversity and a good chance your friends aren’t there. Mastodon excels at meeting new people who share your interests but is less suited for maintaining an existing network of close contacts unless they migrate together. Companies and mainstream media invest far less energy in Mastodon than in Twitter or Instagram, where the audience is massive. Still, for certain niche audiences—open‑source developers, indie artists, digital rights activists—Mastodon offers an engaged, high‑quality community. It’s not a replacement for mainstream social networks for everyone but an alternative for those willing to trade reach for relevance. It’s like joining a private club of enthusiasts instead of a giant public expo.
• Moderation and problematic content: Decentralisation is a double‑edged sword for moderation. Each instance can enforce strict rules locally, but there is no central oversight to remove illegal or harmful content quickly across the network. Studies have found that some illegal content could circulate on Mastodon instances because volunteers lack automated detection tools. The community responds by defederating problematic servers and working on interoperable moderation tools, but the risk remains that malicious groups exploit tolerant instances to spread extreme content. Such content won’t reach you if your instance doesn’t federate with them, but it exists. Legislation and shared ban lists are developing to address this. In general, if you join a reputable instance you are unlikely to encounter shocking content, but overall safety relies heavily on community vigilance.
• Incomplete interoperability and software fragmentation: Mastodon is part of the broader fediverse, which includes services like PeerTube and Pixelfed. This openness means there isn’t a unified user experience: following a PeerTube account from Mastodon may require leaving your client to watch videos. Some features exist in one software but not another. Mastodon has been slower to implement features such as quote posts, choosing to prioritise privacy and network stability. New features arrive gradually and the experience varies depending on the web or mobile client you use. This diversity means you can choose the interface that suits you, but also that you need to experiment a bit—unlike platforms such as Facebook that impose a single interface. It’s a trade‑off of the open ecosystem.

Conclusion

In conclusion, Mastodon embodies a renewed vision of social networks, based on decentralisation, ethics and reprioritising the user over algorithms. It offers a concrete alternative for all—individuals, communities and organisations—who want a free online space without commercial exploitation of their data and collectively controlled. By putting the reins back in users’ hands, Mastodon enables the creation of social environments aligned with our values and specific needs: we can build a small, well‑moderated community, sheltered from the noise of mass platforms.

Of course, joining Mastodon today requires a small adaptation effort and the network does not (yet) have the universal reach of Facebook or Twitter. But the long‑term benefits are significant. From a mental health perspective, it largely avoids the anxiety‑inducing and addictive mechanisms criticised on mainstream networks. From a digital sovereignty perspective, you regain control of your data and of the tool itself (thanks to open source and the possibility of self‑hosting). And from a community perspective, you return to a human‑scale space where you can truly exchange without being drowned in an anonymous ocean.

In short, Mastodon will not immediately replace private giants for everyone—and that is not its mission. Rather, it traces an alternative path: a more human, interoperable and respectful social web. As concerns about the abuses of centralised networks grow (even regulators are trying to legislate on algorithms and harmful content), Mastodon and the fediverse are a breath of fresh air and a return to the original spirit of the Internet: a decentralised, peer‑to‑peer network serving its users rather than commercial interests. If you aspire to a more serene, private and controlled online presence, don’t hesitate to make the leap—many welcoming communities will greet you there. As Mastodon users often say: “Welcome to the fediverse” 😊.

Sources:

• Mastodon – ‘The social network that isn’t for sale’, official overview (2025) joinmastodon.org
• Zoom on Mastodon: another competitor to X – Swello Blog (2024) swello.com
• Renaissance Numérique – Decentralised social networks: toward an ethical Web3? (2023)
• Action Santé Mondiale – Tech & mental health: my network, my tormentor? (2024)
• Stanford Observatory – Study on moderation in Mastodon (summary by Le Clin d’œil Fnac, 2023)
• Electronic Frontier Foundation – What’s the Difference Between Mastodon, Bluesky, and Threads? (2024)
• SocialBee – Mastodon vs Bluesky: How are they different? (2024)
• Privacy Guides – Guide to decentralised social networks (2023)
• Wikimedia Commons – Screenshots of Mastodon (images, CC0); Fediverse logo proposal (image, CC0)