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Copper (Cu) CoAP user-agent (JavaScript implementation)
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chrome Smaller status field Jul 16, 2016
components Upgraded from deprecated protocol handler function Aug 4, 2017
content Fixed #6 Aug 5, 2017
defaults/preferences Added etch support Aug 4, 2017
LICENSE Update LICENSE Oct 14, 2016 Update Oct 18, 2018
chrome.manifest Launcher update Aug 4, 2017
install.rdf Added etch support Aug 4, 2017

Copper (Cu) CoAP user-agent

Implements RFC7252

Also see Copper (Cu4Cr)

Not supported by Firefox 56+ / WebExtensions API

Mozilla changed their add-on model to the WebExtensions API, which does not allow implementing protocol handlers.

Copper cannot be fixed to work again unless Mozilla changes the internals of Firefox again -- not to the old one, but a safe one that allows for protocol handler add-ons.


  • Copper4Cr: Chrome also uses the WebExtensions API, but has a loophole through discontinued Apps installed in developer mode
  • Californium (Cf) Browser: Java-based tool, yet without the debug options support
  • Firefox 55 Portable: Downgrade, but only use for add-ons, not browsing...
    1. Ensure to start offline (no Internet connection!) and disable auto updates
    2. Open about:config
    3. Search browser.tabs.remote.autostart and browser.tabs.remote.autostart.2
    4. Set both to false

A Firefox add-on to browse the Internet of Things

How to integrate the Copper sources into Firefox:

  1. Get the sources from Github: clone git://
  2. Add a text file named to your extension directory of your profile:
  • Windows: C:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles\xxxxxxxx.default\extensions\
  • Linux: ~/.mozilla/firefox/xxxxxxxx.default/extensions/
  • MacOS: ~/Library/Application Support/Firefox/Profiles/xxxxxxxx.default/extensions/
  1. Write the path to the Copper sources (i.e., the directory that contains install.rdf and chrome.manifest) with (back)slash at the end to the file (e.g., D:\Projects\Git\Copper\).
  2. Since Firefox 43 you need to allow unsigned add-ons by opening about:config and setting xpinstall.signatures.required to false.
  3. Restart Firefox.
  4. Optionally use about:config with the filter "copper" to clean up old configurations.

Copper should show up in the add-ons list. You can now enter CoAP URIs (e.g., coap:// into the address bar and will have a user interface to interact with the CoAP resources on a server. The detailed log output is available through the rectangular button on the top right, next to the preferences button.

See also:

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