GuldenTrader was an exchange with recognized service in the Northern countries, especially in Belgium and Germany. This network is no longer available. The information found offers limited content, and it is not so easy to determine what was the reason for this service to be closed. However, the company was very committed and informed their users on time of the closures and measures to take.
Now, everyone who accesses the main page will just see a chart that informs the site is no longer available. Equally, they can withdraw their funds from the page in case some customer has assets saved there.
I recommend users to do it quickly as once the page is finally closed, no one can get access to it. This page is not a risk, but if you saved a big amount of money there you can lose it as you don't withdraw them on time.
NOTE: This service has now negative reviews as it evaporated all their services so fast.