The platform is home to a devoted base of left-leaning communities – and no one billionaire can control it

Since Elon Musk completed his purchase of Twitter last week, some of the social media app’s users have been looking for a new home – only to find there aren’t many great options. Twitter’s co-founder Jack Dorsey is beta testing a new app called Bluesky, but there’s no launch date yet.

However, tech-savvy users are rallying around Mastodon, a six-year-old social media platform popular among a devoted base of left-leaning niche communities. Mastodon, named after the extinct tusked animal, is decentralized, which means it can’t be controlled by a single corporation or space billionaire. That’s clearly appealing to the flood of users who have signed up since Musk’s Twitter takeover, with more than 70,000 users joining Mastodon on the day after his announcement alone.

But that’s still a drop in a bucket compared with Twitter’s reported 450 million daily active users. A big problem? Decentralized software remains difficult for many people to use.

I joined Mastodon this week, and it took a few hours just to master its new vocabulary. Some of it is a little silly-sounding: instead of tweets, you have “toots”. Things get trickier after that. Mastodon is not a single website but a network of thousands of websites called “instances”, also called servers. These servers are “federated”, which means they are run by different entities but can still communicate with each other without needing to go through a central system. And the space they all exist in is called the “fediverse”, which some savvy tooters call “the Fedi”.

When you sign up for Mastodon, the first thing you do is choose a server. There are general-purpose ones, such as mastodon.social, as well as ones aimed at interest groups, such as kpop.social or linuxrocks.online. There are also joke servers like dolphin.town, where the only thing users are allowed to post is the letter “e”.

The server becomes part of your username (for example, wilfred@kpop.social), and the toots you see on your feed are toots from your server-mates, rather than from the entire fediverse. But you’re also free to toot at people from other servers and even “boost” their public toots on to your feed.

That’s how Mastodon creates a unified global experience without being controlled by one entity, said Eugen Rochko, Mastodon’s Germany-based founder and lead developer. “The servers are service providers, like Hotmail and Gmail are for email. It doesn’t mean that the different servers are isolated from each other, like old school forums,” he said. “Having just one account allows you to follow and interact with anyone in this global decentralized social network.”

But Mastodon’s model comes with its own risks. If the server you join disappears, you could lose everything, just like if your email provider shut down. A Mastodon server admin also has ultimate control over everything you do: if for some reason the owner of kpop.social doesn’t like that I boosted a toot from dolphin.town, they could remove it or even “defederate” the server, which would block all dolphin toots from the k-pop server completely. A server admin could also snoop on my private toots if they wanted to – or delete my account for any reason.

Rochko said new users should scrutinize who runs a server before they join it: “Is it an organization that has a track record, is trustworthy, is likely to be around for a long time, but also has a moderation policy?” The “good ones”, he explained, “have rules against hate speech, and provide basic necessities like backups, so if one of the admins gets hit by a bus, the server does not disappear.” Rochko added that Mastodon includes a list of vetted servers on its homepage that meet these criteria. But it’s still a tall ask for a brand new user to figure these things out on their own.

As a result, many of Mastodon’s core users have been tech experts, like stux, a 29-year-old man from the Netherlands who told me over private toots that he’s been “messing around with trying to create an alternate social platform” for “about a decade”. He runs mstdn.social, a server that has amassed 83,000 users over three years and costs him €358 a month, which he crowdfunds through Patreon. He also moderates it: “Many reports are very clearly breaking the rules, trolls, racists etc. But in some cases it’s two people against each other while I am the referee and try to find a good in-between.”

While technically anyone can spin up a Mastodon server, most users agree that the network has a left-leaning bent. Mastodon’s list of vetted servers include queer-themed and climate justice-oriented instances; to be included on the list, a server must agree to the Mastodon Server Covenant, which requires “active moderation against racism, sexism, homophobia and transphobia”. Rochko said his work wasn’t specifically left- or right-leaning but simply abided by “basic, basic beliefs that I have about social networks, and that is, for example, that hate speech should not be allowed”.

The difference between Mastodon and a site like Twitter can feel dramatic. Elilla, a Brazilian trans woman living in Germany, said Mastodon felt much safer to her: because instances can be tightly controlled, people can have discussions without being worried about them accidentally getting broadcast to the world. “What counts as a ‘viral’ post will typically have 50 to 100 boosts. Most of my toots have two to 20 likes,” she said. “But when there’s 20 likes I know most people by name, I know their personalities and tastes and interests. There’s a feeling of reciprocity I never had on Twitter; no one is a celebrity, everyone gets read.”

That’s allowed Elilla to form a caring community through which she’s found deep friendships, romantic relationships, and even jobs. When she decided to try posting erotic content, she “didn’t get hate even once”, she said – something that would be inconceivable on a public site like Twitter. “The fediverse taught me what it it’s like to have community, and the community taught me what is trans joy.”

Unfortunately, Mastodon’s decentralization also means it can be repurposed by anyone for any reason. In 2019, the white supremacist social network Gab started using a version of Mastodon’s free software. Mastodon’s team couldn’t prevent Gab from doing so, but many of the largest Mastodon servers defederated the Gab servers, so that they wouldn’t be able to interact. Mastodon’s code has also been used to power Trump’s social network, Truth Social.

Despite its growing influence, Mastodon’s design makes it difficult to fund, according to Nathan Schneider, a University of Colorado Boulder researcher of tech ownership models – and that makes it unlikely to dethrone a website like Twitter. “Mastodon is a volunteer project that is largely developed by one person. And Twitter is a company apparently worth $44bn,” he said. “If a bunch of users got together and said, ‘Hey, we want to band together and create an alternative,’ their ability to access financing would be far lower than Elon Musk’s ability to access financing.”

But perhaps the real reason it’s hard to beat Twitter is simply because it’s just where everyone is. Paris Marx, a vocal big tech critic and host of the Tech Won’t Save Us podcast, said he has tried Mastodon but couldn’t find much of an audience, unlike Twitter, where he has 35,000 followers and writes posts that often go viral.

“It’s still an influential social media platform. And there’s not there’s not a real equivalent to it, and so people who are interested in what Twitter offers, you know, are kind of stuck here,” he said.

Unable to quit, he does the next best thing: “I block accounts that serve me ads. I don’t pay for things like Twitter Blue,” he said. “I try to make sure that I’m not too financially lucrative for them.”