I’ve been taking a closer look at the world of ActivityPub and related federated social networking standards.
Mastodon is probably the most widely used implementation of ActivityPub today1. Here are some random stats I gathered, current as of yesterday:
- I was able to identify 2,621 public Mastodon instances.
- Across these, there appear to be 1.23M registered accounts.
- In the last week, there were 111k accounts that actively published content.
- The largest single instance is pawoo.net, run by the Pixiv Japanese artist community, which appears to account for a quarter of both registered and recently active users (at 368k and 33k, respectively).
- Three of the top five largest instances, which in sum account for almost 50% of the entire network’s accounts and activity, are based in Japan.
- One of the largest instances is switter.at, an “open and free community for sex workers” that appears to have been created in light of the FOSTA and SESTA bills.
The entire network reports slightly over 121 million “toots” across Mastodon’s entire history; for comparison, it’s estimated that there are 500 million tweets every day — that means a new Mastodon is created on Twitter roughly every six hours.
 Okay, it’s not strictly an ActivityPub implementation; there’s a more involved history that’s not relevant here but is worth reading.