Privacy-First Subject Management for Scientific Research


GDPR Compliance

Researchers disclose the individuals from whom they have gathered data, so that requests for access or erasure can be handled efficiently.

Pseudonym service

Contact details are stored in Castellum so all other databases can work with pseudonyms instead.


Castellum allows you to find potential participants from an existing pool using study specific filters.


You can manage appointments for test sessions.

The General Data Protection Regulation (GDPR) mandates that organizations maintain a comprehensive inventory of the data they hold on individuals. This requirement poses challenges within research institutes, where researchers traditionally have a high degree of autonomy in organizing their work.

Castellum addresses this by serving as a centralized repository, enabling researchers to disclose the individuals from whom they have gathered data. Additionally, Castellum allows to track recruitment consent for these individuals, thereby creating a recruitment pool for future research projects.

Castellum makes answering GDPR requests a breeze.

Thomas Feg, Data Protection Coordinator at MPIB


Castellum strives to be an active community project. A public GitLab repository is used to collaborate on the code. Users share insights and suggestions through a chat group and regular community gatherings.

The last community meeting with talks and workshops took place in Berlin on September 25, 2023 (agenda). The following organisations were represented:

  • MPI for Human Development
  • MPI for Biological Cybernetics
  • MPI for Molecular Genetics
  • MPI for Psycholinguistics
  • Max Planck Digital Library
  • Max Planck Computing and Data Facility
  • Ernst Strüngmann Institute
  • Universität Hamburg
  • University of Applied Sciences Potsdam

If you are interested in becoming part of the community, we invite you to reach out to us at

A workshop during the community meeting 2023

Who uses it?