Being employed at web and advertising agencies, Tanja Mark held roles in project lead and concept designer roles. In 2012 she founded werbefreiheit, the basis to her work as a freelancer. Since then, she provides marketing services to her customers and their products. Meeting the C3S team at the Chaos Communication Congress in 2012 led to a successful co-operation, and she became one of the C3S founders. Tanja Mark holds the role of a Member of the Board of Directors at C3S SCE, where she is in charge of all marketing activities. In 2013, Tanja Mark and her team drafted and deployed the new C3S web site launch.