In my earlier IoT series, we explored Thread networks and protocols—how they form self-healing IPv6 mesh networks designed for low-power IoT environments. We looked at connectivity over UDP and TCP/HTTP protocols, and how Thread devices can reach the internet using a Border Router. In this article, we move one step further by implementing CoAP (Constrained Application Protocol) — a lightweight, REST-style protocol built on UDP and optimized for constrained devices and low-bandwidth networks.