This article reports on six years of experience on the continuous redesign and implementation of a collaborative marking platform to support summative and formative feedback in higher education. The design follows principles of feedback quality, collaboration between teachers and students, and institutional requirements for administrative features. The platform includes modules for printing management, scanning support, on-screen-marking, markers training and peer reviews by students. The goal of the platform is to reduce the cost of providing quality feedback by the reuse of annotations and comments, the use of rubrics, and the collaboration between markers, which can monitor inter-rater agreement through real marking processes.