Gem Version Build Status Coverage Status Code Climate Docker Hub Build Status


This Ruby gem implements client functionality for RFC 7252, the Constrained Application Protocol (CoAP). The message parsing code included is written by Carsten Bormann, one of the RFC authors.

The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and constrained (e.g., low-power, lossy) networks. The nodes often have 8-bit microcontrollers with small amounts of ROM and RAM, while constrained networks such as 6LoWPAN often have high packet error rates and a typical throughput of 10s of kbit/s. The protocol is designed for machine-to-machine (M2M) applications such as smart energy and building automation.

Additionally supported extensions of the CoAP protocol:


Add this line to your application's Gemfile:

gem 'coap'

And then execute:

$ bundle

Or install it yourself as:

$ gem install coap


In your Application

require 'coap''coap://').payload
=> "world"'/hello', '')
=> #<struct CoRE::CoAP::Message ver=1, tt=:ack, mcode=[2, 5], mid=51490, options={:max_age=>60, :token=>366862489, :content_format=>0}, payload="world">

c = '')

See the API documentation at or test/test_client.rb for more examples.

On the Command Line

The command line client supports the basic CoAP methods.

coap get coap://

With Docker

You can skip the install section if you want to use Docker.

docker run nning2/coap get coap://



The code is published under the MIT license (see the LICENSE file).