eExams can potentially improve didactics, efficiency, objectivity, flexibility, accessibility, and even sustainability compared to written exams. However, they also present great challenges such as security, reliability, integrity, as well as the availability of computer rooms of sufficient size. To conduct large-scale online exams, we implemented the “Secure Exam Environment” (SEE) in 2011. The SEE enables online testing in any lecture hall using students’ own devices – and loan devices if needed – while blocking access to unauthorized files or internet pages. After booting the SEE, assessment is conducted via Moodle and additional software (e.g. GeoGebra, Excel or Eclipse) can be used as well. To maintain quality of service, we developed a monitoring solution to control the technical infrastructure of the SEE. As of July 2018, we have conducted 1,605 such online exams with 57,607 students. Moreover, the SEE offers the possibility for slotted exams where students can choose freely the time of their exam within a week. Since technical solutions cannot solve all problems, the organization of eExams is vital to guarantee smooth operations as well as integrity. This paper offers a technical solution for the implementation of a secure and highly available exam environment with the various benefits of eExams, and provides organizational recommendations for the successful roll out of online exams as well as for overcoming technical challenges.