Soapstone от ludeed

Leave a short message on any web page for whoever visits next, and see
what other people have left.

Soapstone has no content script and never touches the pages you browse. A
count on the toolbar icon tells you when the page you're on has messages;
click it to open the side panel, read them, and reply.

Messages are stored in your own atproto repo (the protocol behind Bluesky),
not in a database this extension controls. Sign in with a handle you
already have (Soapstone never sees your password) and every message you
write stays yours: delete it from the dashboard and it disappears
everywhere, because the appview is just an index over public data, not the
source of truth.

Privacy: the extension never sends this page's URL to the server. It sends
a SHA-256 hash of it, so pages with no messages, the overwhelming majority
of anyone's browsing, leave nothing behind that can be read back. Full
details: https://appview.soapstonemessages.eu/privacy

Soapstone deliberately doesn't try to be everything: no anchoring to page
elements yet, no algorithmic feed, no ads, no tracking.