I worked on and currently working on developing a multi-platform(FB, twitter, IG) chatbot. It has a traffic of ~​5​ million messages, ~​50​ million events and ~​1​ million daily active users. Reputed companies/political parties/media houses use the product.
I got to use lot of technologies like, kafka, aerospike, prometheus, multiple AWS features, socket.io, mongo, nodeJS to make the bot scalable with growth & high volumes of conversations.