Are there any live analogues of Google Sidewiki: browser plugin + 3rd party UGC system?

Question

Computer networks

With the help of a browser plug-in, I would like to be able to exchange comments attached to any piece of content on any site, bypassing content owners: to overcome anal moderation and other censorship.
Technically, this could be a browser plugin and a third-party service for storing comments.
Some analogy to AdBlock: to identify page elements, for example. article or comment by id div, and stick a block with accumulated comments on top of the page.
Found on the net traces of a similar idea from Google: Sidewiki (covered in 2011). Is there anything alive today?

Answer 1

There is ttyper.com