Microsoft·Software Engineer·Onsite - System Design / Architecture
May 2026
Microsoft system design round focused on building a cloud console home page, with a heavy emphasis on auth, permissions, and audit logging. The scope was broader than I expected and I spent way too long on the login flow before realizing they wanted me to go deeper on the multi-tenancy and audit pipeline pieces.
- Design the end-to-end flow from a user logging in to seeing their personalized cloud console home page, including how authentication and session handling work.
- How would you enforce multi-tenancy isolation so that a user can never see resources belonging to a tenant they don't have access to?
- Walk through how you'd implement role-based access control, including support for resource-scoped or project-scoped roles, not just global roles.
- What would your audit logging pipeline look like: what events do you log, where do the logs go, and how do you make them tamper-resistant and queryable?
- How would you design the home page data aggregation to meet a p95 latency target under 500ms, given that the page pulls from multiple backend services?
“I started with the standard OAuth/OIDC flow and felt pretty solid there, but then they pushed on token storage, refresh token rotation, and what happens if a token is compromised mid-session.” The rest of the author's notes on Software Engineer interview at Microsoft, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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