The interaction of multiple computer systems during multi-center randomized controlled trials (RCTs) is a hurdle for IT-specialists as well as medical staff. A common workflow for the initial registration of a patient requires the generation of a pseudonym by a pseudonymization service, a manual transmission of the pseudonym to a randomization service, and a manual transfer of the pseudonym and assigned study arm into an electronic data capture (EDC) system. This interaction is often time consuming and error prone due to multiple system changes. Objective of this work is to enhance a commonly used EDC system, Research Electronic Data Capture (REDCap), as a single source of interaction for multi-center RCTs. This is achieved by providing two modules for a seamless integration of a pseudonymization service, i.e., Mainzelliste, and a randomization service, i.e., RandIMI. Thus, no site-specific system changes are required, which increases time efficiency and reduces errors. From a technical perspective, only authentication credentials and firewall exposure for a single system must be managed. To evaluate the usability of our implementation, the system usability scale was employed. The increase of time efficiency was measured in laboratory conditions by a comparison of the time for patient registrations with and without our modules. An “excellent” usability was shown and an average time reduction by nearly 64 %. Both open-source modules are available from the REDCap Repository of External Modules.