Multi-Tenant Authentication — Isolating Organizations Safely
Tenant isolation strategies, shared vs dedicated auth, and building tenant-aware middleware for SaaS applications
Every SaaS application is multi-tenant. The moment you have more than one organization using your product, you're managing multiple tenants sharing the same infrastructure. And the single most catastrophic bug in SaaS is a tenant isolation failure — when Organization A can see Organization B's data.
This isn't a hypothetical risk. Major SaaS companies have shipped tenant isolation bugs to production. The consequences are severe: customer trust evaporates, contracts are voided, and depending on the data involved, you may face regulatory penalties. It's the kind of bug that can kill a startup.
Multi-tenant authentication is the foundation of tenant isolation. Every authentication and authorization decision must be tenant-aware. Let's build that foundation correctly.
Tenant Models
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