You might be interested in this thread, which presents an experiment on adding discussions to existing web pages.

By the way, a new version of my prototype is available at www.docuss.org.

Thanks @yariplus.
I'm having a deeper look. For the system to work, I need to be able to display a list of specific topics.
With Discourse, I use the tag system with the "tag intersection" feature (an URL that lists all topics containing both tag1 and tag2). There is no such feature in nodeBB, am I right?
A better alternative would be to display a list of specific topics depending on a custom field. I've read about custom fields, but how do I display a conditional topic list?
Thanks.

Docuss intends to be a solution for embedding discussions in web pages, to allow for massively collaborative work.

See a demo here (click an orange balloon to open the discussion panel).

I've put some more use cases and demos here.

The current prototype is based on Discourse, but I'm going to have a look at nodeBB to see if the same is possible.

Any comment ?

Thanks @Giggiux. I don't see how you assign a category to a topic, either when you create the topic or at a later stage.

I don't see this feature in the API endpoints. Am I missing something?

I am a web developer, new to nodeBB.

I am working on a web app where users can discuss a document (see the prototype here; I am in the process of simplifying the UX and planning for version 1). The UI looks like this:
-- a main area shows the document,
-- in other areas/windows/tabs, users can create topics to discuss parts of the document.

Does it sound feasible with nodeBB? My main concern is not OAuth/SSO, but client-side display.