Arathorn, thanks for responding to comments here. Public discourse comes in all flavors and I appreciate you taking time to respond to the queries and comments. :)

AFAIK, there are 6 server implementations of Matrix protocol: Synapse (Python), Dendrite (Go), Conduit (Rust), Construct/Charybdis (C++), Plasma (Elixir), Jeon (Java). Are there any more that I have missed? Which ones other than Synapse are most mature? An unbiased comparison post (that remains updated) would be really useful.

A second question is: are the APIs between a homeserver and the frontend defined and standardized? I've noticed this in the ActivityPub ecosystem where it is usually very easy to use one frontend with another backend. Are matrix servers also written in the same way?