WebClients@v6DEMON – Monitoring IPv6 on the end-users side

This tool aims at monitoring the IPv6 connectivity of web clients, e.g. web browsers.


This script gives the IPv6 Observatory the possibility to monitor IPv6 deployment on the end-users side. By using a piece of Javascript code executed on web browsers, various anonymized data are collected: does the client support IPv6? if yes, which protocol is chosen when both IPv4 and IPv6 are available on the server? Through which ISP was used? …

How it works

This tools uses a technique already deployed by various IPv6 monitoring tool (see the references section below): it tries to access a remote resource using IPv4 and IPv6. Steps are described below:

  • The user visits a website ;
  • The v6demon script is downloaded and started ;
  • The script tries to access an image, through 3 distinct URLs: 
    • IPv4 only URL (e.g. the FQDN -Fully Qualified Domain Name- has only an A record)
    • IPv6 only URL (e.g. the FQDN has only an AAAA record)
    • IPv4 and IPv6 (e.g. the FQDN has both an A and AAAA records)

Please note that:

  1. The script is run only once per day (thanks to a cookie) ;
  2. The script runs asynchronously, thus the page is not blocked during the test. 

How to integrate it on a website

The integration on a website is straightforward: visit the v6DEMON tool website and create an account. Registration is done through a Google account (in case you don’t have a Google account but still want to use the script, you can also create an account directly on the website). Then navigate to the “probed websites” page, add your websites (you can monitor multiple websites). Each time a webpage is added, a piece of Javascript code is generated. Simply copy and paste this code on your website, right before the closing tag.

The code to be added on your website should look like the code below, with the ABCDEFGH string replaced by an identifier associated to your website

Retrieving statistics

Figures are available when logged in on the v6DEMON tool. At the time of writing, only two figures have been made available (proportion of IPv4 versus IPv6 users and IPv6 users evolution over the time). More figures will be added in the incoming weeks.


The IPv6 Observatory study does not collect any personal data: even those which could be considered as private (e.g. the IP address) are not conserved.

Source code

As per version 1.0, the source code is the following:


In case of problem, please get in touch with us through our contact form.