This thesis evaluates the effects of the GDPR using a technical and human-centric approach. We assess challenges service providers face when they want to design GDPR-proof web applications. On the technical side, we perform two large-scale measurement studies. The first study aims to illuminate third party loading dependencies in web applications. The second study provides a detailed analysis of the information-sharing networks between online adver-tising companies. The human-centric analysis studies how companies implemented the Right to Access and if users can profit from the new right.