An Introduction to Mastodon.org for Friends of Critical AI
By Andi Craciun, Critical AI@Rutgers Research Assistant
Overview: In the wake of Elon Musk’s takeover of Twitter, Critical AI has set up an account on the Mastodon social media network. His changes to the platform conflict with our core mission and values. CriticalAI @ Rutgers and Critical AI (our new journal) will begin to post regularly on Mastodon. (We will likely keep the Twitter account intact though relatively inactive: that way people can find us with ease.) What follows is a user’s guide to Mastodon including information on an app that enables you to post simultaneously on Mastodon and Twitter.
Why Mastodon? How does it Work?
Mastodon is a growing social media network started in 2016. It is a non-commercial site that does not sell data or advertisements. Mastodon is considered part of the fediverse, an assemblage of interconnected servers used for web publishing, networking, and file hosting. These servers communicate with each other despite being independently hosted. When you think of Mastodon, think of a network of servers that communicate with each other.
Instead of a single platform like Twitter, Mastodon’s network is composed of interconnected servers that are called instances on Mastodon (for example, Mastodon.social, Mastodon.technology, or Mastodon.democracy.town). The developer of Mastodon likens this cross-instance communicability to emailing people. Someone with a Gmail account can still email someone with an Outlook, Yahoo, or university account and vice versa.
For those interested in Mastodon’s early history, see this interview from Slate.
Like Twitter, Mastodon is a microblogging platform. On Mastodon, “tweets” are called “posts” but provide almost double the space (500 characters). There are a few other important differences between Mastodon and Twitter (which we will explain below). But first, the basics.
I . Registering
Registering on Mastodon is simple! Here’s how to join us.
Step 1: See if it is possible to join Mastodon.social, the instance where our Critical AI Mastodon account is located (sometimes it’s full in which case you might try another Mastodon instance such as those listed here). If you can sign up, enter your information as prompted.
Step 2: You’ll have to verify your account, so log into your email and look for a message from Mastodon. It could take a few days for you to get this email, since there could be a large number of people joining the Mastodon.social instance, making it difficult for the moderators to get back to everyone immediately.
Step 3: Once you receive the email and your account has been verified, log in by going to the same Mastodon.social website.
Step 4: You’re almost set! Locate the search bar on the top left of the webpage and look up CriticalAI.
Our account will be the first search result that shows up, and if you click on it, you’ll be able to follow us.
Step 5: Edit your profile to your liking and start posting. We can’t wait to see you there!
It’s important to note that you can make Mastodon accounts for as many instances as you want and, in most cases, logging into one instance provides you with access to the content for other instances (as we will explain). The largest and most topically diverse of the instances is Mastodon.social, where the CriticalAI account is located.
*You might find that Mastodon.social is fully subscribed (this fluctuates) in which case you can join one of the many other instances that are part of the “federated” timeline. To follow CriticalAI from a separate instance, you will need to join an instance on a connected server.
The majority of servers do communicate with each other, but there are a select few that do not. If you join one of the instances that does not have this connection, you may not be able to access our content.
This website allows for users to check how many other instances their server is connected to. Mastodon.social, for example, is connected to 23425 instances. The higher the number of connections, the more content you’ll be able to see.
II. Timelines.
Unlike Twitter, Mastodon’s timeline is chronological–not algorithmically curated. Your “home” feed will include the posts of the people/accounts that you follow; but you also have the option to read two additional timelines: local and federated. The local timeline (designated by an icon of a group of people) is a stream of posts from everyone posting publicly on that particular instance. The federated timeline (designated by a globe icon) includes all users across various interconnected instances.
By looking at the federated timeline, Mastodon users can (usually) follow other users (whether they are followers or not) on other instances* Here is a list of instances.
III. Privacy Options.
Mastodon offers the ability to make posts public, unlisted, private, or direct. Public posting, which is what Critical AI will be doing, will enable our posts to be visible on the local, federated, and global timelines. (Private posts only go to followers, direct posts only go to users).
IV. Searching.
Mastodon doesn’t enable you to search for the content of individual posts. That means that if you put a random word (e.g., cats) in the search bar, the result will not return posts, only cat-related hashtags (#) and usernames – but that’s only if the hashtag or username contains the exact word in the result. Here’s an example:
How Can I Switch Over From Twitter to Mastodon?
I. Starting a Mastodon account.
- Choosing an instance.
In choosing other instances that may work for you you should think about two different things: a) the interests of that instance’s users and b) its connection to other instances. Note that it is possible to change one’s instance (if, say, you want to join Mastodon.social after previously joining another instance). See more about migrating accounts below.
- Starting an Account.
As mentioned previously, Mastodon.social is the largest instance, and its availability fluctuates when accepting new members. To join us, please join Mastodon.social and search for CriticalAI (as detailed above) or join another instance and then find us here.
Here’s another way to start a personal account. Go to https://joinmastodon.org/ and click
“Get started” to begin.
You’ll then be prompted to choose a server, with a set of categories. For the purpose of this tutorial I’m going to scroll down in the “General” section and select Mastodon.social, where Critical AI is.
This is the initial page of servers you can look through. Scroll down to find the following box:

If you click “browse directory” by the buttons that say “Join” (note that the join button will only appear for servers accepting new users), you can see a list of users. CriticalAI is somewhere in there!
As shown in the section above, it’s as simple as choosing a username, entering your email, and making up a password. At that point you will be able to check the server rules for this instance and click “Sign Up.”

You’ll get a confirmation link at your email address (this may take some time given the heavy traffic but make sure to check Spam if it doesn’t show). After verifying your email address, you’ll be taken to your new home page!
It looks like Twitter and from here on should be fairly intuitive. See step 4 in the above section about registration to figure out how to find us, or follow this link to our account.
Users can talk across instances, and if you go to your local or federated timeline, accounts from other Mastodon instances will be recommended for you to follow, even though you’ll be on the separate Mastodon.social instance. Using Mastodon.social will be fairly intuitive to anyone accustomed to Twitter!
How Do I Move from Twitter to Mastodon?
Unfortunately, it is not as simple to move information from Twitter to Mastodon. This must be done manually. The best way to do this is by asking friends if they’re moving and informing Twitter followers about the switch over.
It is also important to note that there is no way of importing Twitter information, such as an archive, into your new Mastodon account.
How Do I Simultaneously Post to Mastodon and Twitter?
If you want to gradually transition from Twitter to Mastodon, you can continue posting to Twitter while sharing those same tweets to Mastodon. Initially, this was done through websites like IFTTT, which automated sharing to both sites, but now posting and tweeting simultaneously has become much more simple. Websites like Crossposter or Moa both require you to have a Twitter and Mastodon account already set up in order to link the two.
Moa will initially prompt you to log into Mastodon and Twitter and then will prompt you to authorize the platform to write posts for you on both the aforementioned social media sites. After logging into Mastodon and providing the necessary authorization, you can log into your Twitter account and do the same, and the bridge between your Mastodon and Twitter accounts will be complete.
Crossposter is a website like Moa which works similarly, with the only difference being that you can choose which account to log into first when starting the bridging process – otherwise, the process is the same, with the need to authorize Crossposter to access both your Mastodon and Twitter. This website is generally more favored by those on Mastodon as it was made by a Mastodon user and so is more closely curated for posting between those specific websites. However, do keep in mind that if you join an instance not supported by the Crossposter (if this is the case, you will see “Sorry, <instance> is blocked in this instance” when you try to login to the crossposter) then Moa is still a good alternative option.
Media like .jpg and .png files should transfer between posts. Be advised that while photos typically make it through, on occasion larger files will have difficulty showing up. Unlike any files you may be posting, please note that Mastodon-specific emoticons won’t show up on Twitter, and website-specific hashtags will behave differently from site to site (for example, #FuturePerfect was trending on Twitter but will not show up on Mastodon since no one’s used that particular tag yet), so if you’re trying to promote your Mastodon post and tweet simultaneously, sticking to more general hashtags is a good rule of thumb, as it will typically get you more interactions.
You can post or tweet from whichever account you choose, but be warned that it may take a few minutes for what you wrote to show up on the other account, so don’t panic if you don’t see it immediately!
What will happen to the Critical AI Twitter account?
The Critical AI Twitter account (@CriticalAI) will remain up as an archive of the past, as well as a signpost for where to find us in the future. We hope it will be a prompt for others to move from Twitter to new platforms, for reasons stated in the “Why Mastodon?” section.
Who to Follow.
Here’s a list of people who have migrated over to Mastodon, with their accounts and instances listed. They can be found by looking up their names.
CriticalAI (@CriticalAI@mastodon.social).
Sasha Costanza-Chock (@schock@mastodon.lol).
Timnit Gebru (@timnitGebru@dair-community.social)
I already have a Mastodon account, but it’s not on the Mastodon.social instance. Can I still switch over to join CriticalAI?
You can! Here’s how to migrate across Mastodon. Mastodon allows its users to transfer accounts from instance to instance, meaning you are not limited to one server. Even with the migration, you keep your followers and posts.
First, log into your old Mastodon account (the one you wish to move from) and go to the Data Export tab under the “Import and Export” tab, where you can download a list of followers and get a copy of an archive of all your posts and media, so you have a copy of all your posts.
Next, follow this process.
- Sign up with an account on the new server you want to be on.
- On the NEW SERVER, go to: Account → Moving FROM another account.
- Enter the old account’s handle as prompted.
- On the OLD SERVER, go to: Account → Moving TO another account.
- Enter the new account’s handle as prompted. Submit it.
Note that this does not migrate posts, it only moves the account from one instance to another. To migrate posts and followers, you need the copy of the archive exported from your old account previously to moving, which can be imported into the new account under the “Import” tab of the “Import and Export” page.