This site puts numbers on a question people argue about a lot: are the Fediverse and Bluesky actually decentralized, or is everyone just on one big server? It measures how concentrated users are across servers and compares that to the rest of the internet.
What it measures
- Mastodon and other Fediverse servers by monthly active users.
- Bluesky users per personal data server (PDS).
- Web hosting and CDNs, git forges, email providers, DNS hosting and certificate authorities.
- Each gets a Herfindahl-Hirschman Index score, the same measure regulators use for monopolies, plus a Shannon diversity score.
How it works
Rob Ricci built it. Fediverse numbers are scraped daily, Bluesky data comes from relay monitoring, and the rest pulls from published research and public datasets. The code and data are open on Codeberg. An HHI near 0 means lots of competition and near 10,000 means one player owns it all, so you can see at a glance how lopsided each network is.
Why I saved it: real data for the next time someone says Mastodon or Bluesky is or is not decentralized.