This looks quite exciting. I hope to get the time to test it.

There's of course Hypothes.is, which is an open standard, but this being built on Matrix makes it all new and shiny :-)

Annotate the web, with anyone, anywhere.

I have enabled the hypothes.is sidebar on my blog since its inception.

• Annotation is now a web standard via lobste.rs
• Using annotation as a blogger, video recording of talk by Tom Critchlow at "I Annotate 2019"
• How to subscribe to the Hypothesis public stream for an entire domain using RSS
• A coalition for scholarly annotation
• Viewing and exporting Hypothesis annotations