Threads, the micro-blogging app from Meta, has announced their intent to implement ActivityPub and join their user base to the rest of the Fediverse.

At this time, Threads has very limited federation abilities:

  • You are only able to follow accounts that Meta has enabled ActivityPub support like their engineering leader Adam Mosseri and a few others
  • Threads users cannot follow you at this time
  • Any likes, boosts or replies you make are seen by users but are not seen by Threads users that you follow

Meta controls how much they federate and when, Mastodon instances are generally compatiable with any other ActivityPub deployment.

Known Issues

Some members have experienced issues following users on, where the requests are stuck in a state of pending approval, but the Threads users are not able to approve it. This is not anything specific to and users from other instances have reported the same issue.

We use a feature known as "authorized fetch" which is essentially a security feature that uses signed requests for ActivityPub data. It prevents instances or users that have been blocked from obtaining post data when they shouldn't be. It is not enabled by default in Mastodon.

At this time Threads doesn't seem to have proper support for instances with authorized fetch enabled, but their engineers are aware of it we we assume this will be resolved soon. This is also not a problem specific to Threads and their implementation of ActivityPub, as there are other non-Meta software implementations of ActivityPub which sometimes fail to properly implement this feature.

Defederation Questions

Some Mastodon instances have announced proactive defederation from the domain, and some have gone further and agreed to defederate from any instance that does not also defederate from Threads.

While we are supportive of administrators choosing to disconnect themselves from whatever instances they choose, we would take exception with this second-order level of defederation and consider that harmful to the health of the entire Fediverse.

At this time does not plan to defederate from Threads, although we may take action to restrict some Threads users or limit some Threads posts from appearing in federated timelines depending on their content, just as we would with any other instance.

Privacy Implications

Mastodon instances do not broadcast private data like email or the IP address you use to other instances. The software is built on the reasonable assumption that third party servers cannot be trusted. servers download, process and cache images and videos for you to view. Not only is this more efficient when multiple users want to view the same content from another instance, it helps to preserve your privacy by acting as a proxy to that resource. Unless you choose to click through to the source content the originating server cannot get your IP address, browser name, or time of access.

Meta, or any other instance that we federate with, cannot fingerprint or use other private data or track you across the web simply by us being federated with them.

Some folks are concerned that content posted on their instance will be federated to Meta when someone using Threads follows them, allowing Meta to index that content. While this is a valid concern, Mastodon provides controls for individual users to block any domain they choose, so if this is a concern you can defederate yourself from Threads at any time while remaining a member of However, if your Mastodon account page (ex: is already publicly accessible, search engines and other systems can already index your posted content.


Nobody on Mastodon can insert advertising into your user interface, unless you use a third-party client app that is funded that way. Unless you use Threads, you will not see any ads from Threads.

The Mastodon software does not include any functionality to display ads in the web UI or the official mobile app, and will never add the ability to do so as we are not funded by advertising.

It is not possible for any third party server to insert ad-like posts into your home feed, since your home feed is calculated by your own server from the people (and hashtags) that you choose to follow.

If someone you follow makes a sponsored post and you do not want to see it, you can unfollow or mute that person, just as if that other person was on a Mastodon instance.