Are you mabe thinking of Solid[1]? This is an interesting idea, and I have looked into it on several occasions recently, but despite it being around for a really long time it appears to be going exactly nowhere, unfortunately.

It seems a bit of a missed opportunity really. If they had more agressively pursued alliances, it could potentially have been a solid (pun only semi intended) foundation for Mastadon and Bluesky.

The name is unfortunate as well, it is really difficult to search for.

[1] https://en.wikipedia.org/wiki/Solid_(web_decentralization_pr...