The original English version of the Test Item Design Support Tool can be found here: http://testdevelopment.nl/qdst/qdst-en/default_dive_conv.html. You need to allow your browser to display ‘unsecure information’. Look for a shield icon in your browsers address bar (when you are on the site) and click on it to allow this.
The Test Item Design Support tool of Silvester Draaijer formed the basis for the qDNAtool of which you now reached the support pages. The public accesible qDNA tool can be reached here: http://qdnatool.org/users/login. You need an SURF Insitutional Account to access the application, but an Open Source version of the application can be found on Github: https://github.com/nlware/qdnatool.