The talk is about Trixity, a matrix SDK that can be used to develop clients, bots, app servers, and servers. It is written in Kotlin and is multi-platform capable. The speaker explains why they created Trixity, highlighting the lack of multi-platform SDKs and the limitations of existing ones. They discuss the advantages of using Kotlin, such as its compatibility with different platforms and its ability to define a domain-specific language. Trixity consists of several layers, including the core, API, ARM, Crypto, Client, and App Service. The speaker also explains how they accidentally created a cache in Trixity and the benefits of using timelines instead of fragments. They provide a small example of how to write a bot using Trixity and mention other projects that are using it. They conclude with a performance comparison demo and answer questions from the audience.