LUCET’s in-house online assessment system OASYS can be considered the centre’s technological backbone. OASYS is a multi-platform and multi-device digital testing and assessment system built around state-of-the-art web-technologies. In close collaboration with the University’s Human-Computer Interaction (HCI) research group, OASYS has been carefully designed around business processes, following a research-based HCI approach, thus ensuring optimized user experience. To assure secure data collections and best-possible service, OASYS offers powerful live monitoring for test administrators. Every response is communicated and logged instantaneously on LUCET servers, which minimizes the loss of data even during potential client side computer crashes. Speaking of security, OASYS developers undergo regular security training, and OASYS underwent state-of-the-art penetration testing and code review by external security consultants. OASYS collects timestamps of every action, thus making the platform an ideal choice for behavioural analysis and data mining. A load balancing solution allows for around 20K simultaneous client connections in the current server setup. Notably, all OASYS servers are hosted in-house, thus facilitating GDPR compliance. Although OASYS has been designed primarily as an online assessment system, the client can also run in an app with a server installation on a laptop and a mobile Wi-Fi access point, thus allowing for digital testing in areas with poor or no internet connection. Since 2010, OASYS is used successfully in the Luxembourg school monitoring programme ÉpStan. Moreover, since 2014, OASYS is also the platform of choice for student course evaluations and various in-house surveys at the University of Luxembourg.