Saas-Architecture

Your app performs well with MemoryCache for 1K users. But when traffic scales to 10K users across three load-balanced servers, cache misses explode and response times spike to 800ms. I’ve seen production APIs crash under load because the team relied solely on MemoryCache. Here’s how we fixed it with hybrid caching strategies that combine the speed of local memory with the consistency of distributed cache. TL;DR MemoryCache works for single servers but fails in distributed environments Hybrid caching uses MemoryCache (L1) + Redis (L2) for best performance Multi-tenant apps need tenant-scoped cache keys to prevent data leakage System.Text.Json provides the best balance of performance and debuggability Monitor cache hit ratios per tenant and cache level for optimal tuning MemoryCache works great for single-server applications, but it hits hard limits in distributed environments. This guide covers hybrid caching strategies that keep your multi-tenant ASP.NET Core apps fast and scalable, with real benchmarks and production-ready code. ...

TL;DR In multi-tenant SaaS, generic audit logging can easily leak data between tenants. This is a security and compliance nightmare. Overriding DbContext.SaveChanges() is a common but clunky solution that tightly couples auditing logic to your data context. EF Core Interceptors provide a clean, decoupled way to hook into the save process and add per-tenant audit logs automatically. The solution involves creating a SaveChangesInterceptor, grabbing the current TenantId from a scoped service, and logging entity changes before they hit the database. This pattern is perfect for auditable, compliant SaaS applications but might be overkill for simple, single-server projects. I once got a panicked call about a critical bug. An admin from “Company A” could see user creation events from “Company B” in their audit trail. It was a classic multi-tenant data bleed, but not in the main application data—it was in the logs. This is one of those sneaky bugs that passes all unit tests but can absolutely destroy trust with your customers and fail a compliance audit. ...

Bad middleware doesn’t just break requests, it breaks entire tenants. Learn the anti-patterns to avoid in your ASP.NET Core SaaS architecture and how to fix them.