CoAPia

CoAPia is a lightweight implementation of the Constrained Application Protocol (CoAP), a specialized Internet application protocol designed for simple devices in the Internet of Things. The project was created to provide an easy-to-use, standards‑compliant library that enables developers to integrate CoAP communication into embedded systems, sensor networks, and cloud services. CoAPia follows the specifications defined in RFC 7252, including support for block transfers, observe relationships, and multicast discovery, thereby ensuring interoperability with other CoAP‑based devices and platforms.

The library is written in C++ and offers a straightforward API that abstracts the complexities of the CoAP message format. It includes facilities for message creation, parsing, and transmission over UDP, as well as timers for retransmission and block-wise transfer sequencing. CoAPia also implements the security extensions defined in RFC 9146, allowing DTLS‑based encryption and authentication for secure data exchange. The API is intentionally minimal, making it suitable for resource constrained environments where memory and processing power are limited.

CoAPia is distributed under an open‑source license, which encourages community contributions and adaptation for specific industrial or research applications. Regular releases are maintained on GitHub, with documentation that covers installation, configuration, and example code snippets. Because it provides a direct mapping to the CoAP protocol stack without the overhead of larger protocols, developers can deploy it on microcontrollers, Raspberry Pi devices, and other low‑power embedded hardware. The project has been adopted by academic research labs that require reliable, low‑latency communication for remote sensing and actuator control, demonstrating its suitability for both prototype and production deployments.