Castor EDC server locations


We have always stored study data locally within the selected region, but our user database was globally stored in the Netherlands. We have implemented the change to split our user database between the stand-alone regions. This means that the user details of users with access to US server studies will only be stored in the US region, while this data used to be stored in the EU region. The study data is not affected in any way. Accounts will no longer be shared between regions. This means that if you need access to studies in more than one region, you will need accounts in both regions.

Consult our user manual if you would like to have more information on the server split or can't login on a different server:

Server: selecting data storage location

Why does my password not work on a different server?


  • When logging in to Castor, you are given the option to choose which server you want to access.
  • Your Castor account details are valid for all servers.
  • It’s possible to have data on multiple servers.
  • For example, if you are participating in two studies, one located on the UK server, the other on the US server. 
  • The server that is selected by default depends on the url where you are located:
  • US server -
  • UK server -
  • Dutch server - 
  • If you were invited to a study by another user and do not have your own study, then you should leave the server location as it is.
  • When logged into Castor, the ‘My Studies’ overview will display all of the studies you are participating in, even if some of these are located on a different server.
  • If you open a study that is located on a server that is different from the one you initially logged in to, you will be redirected and will need to re-enter your login details to access the server and open the study.