WebCSD uses technology called websockets to communicate with CCDC servers during a structure search. We have identified an incompatibility between this technology and some proxy servers, notably EZproxy which is used at some academic institutions, particularly for off-site access to web services like databases and journals. We hope to provide alternative mechanisms as these become available in coming months. We are interested in hearing of any problems you experience so we can better understand the scale of the issue and the affected systems. Please contact us at

The following are suggested workarounds for this problem:

  1. Depending on your institution's network configuration, it may well work when connected on campus if a proxy is not used in this case.
  2. Often times, wired computers such as those that might be at your institution's library, will not use a proxy.
  3. You should be able to register and log in individually to WebCSD using your institution's licence and have structure searching work from a home internet connection when not connected to a VPN. This will require you to register for an account at the CCDC website, or log in to an existing one, and link your institution's license information to your account. If you do not know your license information, it is available from your institution's site contact, commonly a science librarian. If you do not know your site contact, please contact CCDC support ( for their contact information.

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