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B2B SaaS Migration Azure

Enterprise SaaS platform to .NET 8 with phased cutover

Anonymized engagement for a multi-tenant B2B product: move a revenue-critical .NET Framework API to ASP.NET Core without a big-bang weekend.

Anonymized case study. Client name and identifying metrics are withheld. Patterns reflect representative senior .NET programs.

Developers planning a .NET cloud migration

Executive summary

A North American B2B SaaS vendor ran a monolithic .NET Framework 4.8 API on Windows VMs. A senior .NET squad introduced a strangler at the API gateway, migrated two bounded contexts first, and moved traffic in waves to ASP.NET Core 8 on Azure App Service.

0Revenue-path outages during cutover waves
<5 minCanary rollback window (design target)
↓ p95API latency after observability tuning

The challenge

The legacy API mixed HTTP, EF6, and background triggers in one deployable unit. PCI-adjacent patching cadence and release risk blocked quarterly feature delivery.

Technical approach

Strangler routing at the gateway, dual-write for two bounded contexts, EF Core parallel models, App Service slots with contract tests on every swap, and OpenTelemetry traces tied to correlation IDs.

Outcomes

Revenue paths migrated without customer-visible billing outages. Feature teams resumed quarterly delivery on the new stack while planning the next strangler slice.

ASP.NET CoreEF CoreAzure App ServiceOpenTelemetry

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