libcoap 4.3.3

A C implementation of the Constrained Application Protocol (RFC 7252)

Copyright (C) 2010–2023 by Olaf Bergmann bergm.nosp@m.ann@.nosp@m.tzi.o.nosp@m.rg and others

About libcoap

libcoap is a C implementation of a lightweight application-protocol for devices that are constrained their resources such as computing power, RF range, memory, bandwidth, or network packet sizes. This protocol, CoAP, is standardized by the IETF as RFC 7252. For further information related to CoAP, see or CoAP Wiki.

You might want to check out libcoap-minimal for usage examples.

The following RFCs are supported

There is (D)TLS support for the following libraries

  • OpenSSL (Minimum version 1.1.0) [PKI, PSK and PKCS11]
  • GnuTLS (Minimum version 3.3.0) [PKI, PSK, RPK(3.6.6+) and PKCS11]
  • Mbed TLS (Minimum version 2.7.10) [PKI and PSK]
  • TinyDTLS [PSK and RPK] [DTLS Only]


This set of pages contains the current set of documention for the libcoap APIs.

License Information

This library is published as open-source software without any warranty of any kind. Use is permitted under the terms of the simplified BSD license. It includes public domain software. libcoap binaries may also include open-source software with their respective licensing terms. Please refer to LICENSE for further details in the source.