Authorization at scale for a multi-tenant SaaS platform

The problem

A multi-tenant API-gateway platform needed fine-grained access control across org, project, and resource scopes — without misconfiguration bugs or slow permission checks getting in the way of every request.

The approach

• ▸Designed a Google Zanzibar-style ReBAC system: a declarative policy language defines role-based access, then compiles down to relation tuples via diff-based reconciliation.
• ▸Built a code generator that reflects over controller decorator metadata to compile proxy access rules at startup — so rules can never drift from the code they protect.
• ▸Modeled the org → project → resource scope hierarchy so a single policy expresses access at any level.

The outcome

• ✓Runtime permission checks resolve in under a millisecond.
• ✓An entire class of misconfiguration bugs is designed out — rules are generated, not hand-written.
• ✓Access rules stay in sync with the code automatically, with no manual configuration step.

Stack