This guide is for Matrix developers who want to support MSC3079: Low Bandwidth CS API in their clients/servers. Please read the experimental MSC if you want to learn more about what is happening at a protocol level. If you want a high level overview of low bandwidth Matrix and why you should care, watch the 12 minute demo on Matrix Live.
Matrix currently uses HTTP APIs with JSON data to communicate from the client to the server. This is widely supported but is not very bandwidth efficient. This means that the protocol is slower, more costly and less able to be used on low bandwidth links (e.g 2G networks) which are common in certain parts of the world. MSC3079 defines a low bandwidth protocol using CoAP and CBOR instead of HTTP and JSON respectively. In the future homeservers will natively support some form of low bandwidth protocol. However, at present, no homeserver natively supports MSC3079. Therefore, this guide will set up a low bandwidth proxy server which can be put in front of any Matrix homeserver (Synapse, Dendrite, Conduit, etc) to make it MSC3079-compatible. This guide will also configure an Android device to speak MSC3079.
Low bandwidth Matrix currently does not support web browsers due to their inability to send UDP traffic. You do not need to be running a homeserver to follow this tutorial.