Abstract
While agile methods have had a great uptake and impact in software engineering, managing non‑functional qualities still seems to be a challenge. We focus on the scalability of software systems and how this critical quality can be managed and controlled, while still benefiting from the advantages of an agile process. Scalability is a property of a system that must be carefully designed in to avoid potential disastrous behavior when load and work fluctuate. Through a collaboration with and a case study at the largest Norwegian public portal operator, Altinn, we have proposed and tested additions to the Scrum process framework. With our approach named ScrumScale, scalability concerns may be identified and related to user stories. The roles in a Scrum project can collaborate without adding more ceremony than strictly necessary. The paper provides an overview of the ScrumScale method and lessons learned from Altinn.