Marc focused on backend stability and standards compliance across two projects, addressing critical bugs in authentication and API behavior. On thoughtbot.social, he improved OIDC onboarding by implementing a truncation mechanism for display names, preventing account creation failures caused by excessively long inputs and establishing a reusable sanitization pattern for future identity providers. For THM-Health/PILOS, Marc enhanced RESTful compliance by removing unnecessary Content-Type headers from empty HTTP GET requests and aligning tests with real-world semantics, resulting in clearer API behavior and more reliable test outcomes. His work utilized Ruby on Rails and PHP, emphasizing backend development and robust unit testing practices.