Azure multi-tenant SaaS architecture using Front Door, Application Gateway, and App Service to route custom domain requests across isolated tenant databases. Traffic flows from tenant domains through Azure Front Door and Application Gateway to App Service, which queries a Tenant Resolution Service to identify the correct tenant metadata and SQL database connection. This pattern isolates tenant data in separate Azure SQL Database instances while centralizing configuration, secrets, and monitoring through App Configuration, Key Vault, Monitor, and Application Insights. Fork this diagram to customize subnet ranges, add API Management, or implement additional isolation layers for compliance-heavy workloads. The architecture demonstrates tenant routing best practices, reducing blast radius and enabling per-tenant scaling and backup strategies.