This really should have been called Round-less Deliberation.
That's because the definition I am using is that there really is no direct conversation; all communication is based this:
In the context of some probe, say a statement such as "Climate change is caused by greenhouse gas", participants, typically, react to that statement on a sliding scale of disagree to agree, then explain, in a text box, why they made that choice.
What happens after that depends on the platform. Following is the beginnings of an enumeration of platforms known to me.
Pol.is is an early platform in which users actually write statements in the context of some probe, then vote up or down on each other's responses. The platform clusters responses. a "conversation" occurs indirectly as participants scan other responses and the clusters, possibly changing their response.
Real-time Delphi presents a list of probes, and users respond with a sliding scale, then write their reasons. In the specific context of a given probe, participants can see all the other anonymous responses. No voting. The "conversation" lies in how a given participant reacts to other responses.
deliberation.io offers a probe, you respond with a sliding scale, then explain your reason. This platform uses AI to read your response and probe further for several cycles. At the end, it asks you to vot up/down/pass on at least 3 other responses, then asks you the initial probe again to see if you moved.