There is the main python implementation Synapse, there are two Go implementations (Dendrite and the other chinese finance chat implementation) , one very active and one nearly dead Rust implementation, a half baked c++ implementation and some others.
This is the Chinese implementation. From the README and website it seems its being heavily used in production but the website is Chinese so I dont know for sure.
On first read I just saw "...nearly dead Rust implementation" and didn't notice the previous fragment saying there was another very active one. Just a reading comprehension fail but maybe the sentence structure tripped up others like it did to me.
