Building a B2B SaaS platform for transport companies, I faced a critical architectural decision: separate database per tenant or shared database with logical isolation? I chose shared database. Here's why and how I implemented bulletproof data isolation with pure Laravel. Why Shared Database For a B2B SaaS, database evolution is critical: Pros: Atomic migrations (add a column once, not 500 times) Simplified backup/restore Lower infrastructure costs Cons: Logical isolation (not physical) Noisy neighbor risk If I ever reach 500 tenants, managing 500 separate migrations per feature would be a full-time job. Shared DB wins. The Architecture USER REQUEST │ ▼ MIDDLEWARE (EnsureTenantAccess) │ 1. Verify authentication │ 2. Extract tenant ID │ 3. Store in TenantContext (singleton) ▼ ELOQUENT MODELS (with BelongsToTenant trait) │ 4.…