Microservices vs Monolith in .NET: When to Choose Which
Microservices are not always the answer. We break down when a .NET monolith or modular monolith makes more sense than jumping to microservices — and the criteria we use with clients.
The Microservices Hype Problem
Every enterprise architecture conversation eventually arrives at the same question: should we go microservices? The honest answer is: it depends — and that dependency matters more than most teams realise.
At VFL Technologies, we have delivered both monolithic and microservices .NET solutions across 200+ projects. The pattern we consistently see is that teams choose microservices for the wrong reasons: because it sounds modern, because a consultant recommended it, or because a competitor is doing it. The result is often a distributed monolith — all the complexity of microservices, none of the benefits.
When a .NET Monolith Is the Right Answer
A well-structured .NET monolith is not a legacy choice — it is often the correct engineering decision. Choose a monolith when:
• Your team is fewer than 15 developers • Your domain boundaries are not yet well understood • You are building an MVP or validating a product • Your traffic is predictable and does not require per-service scaling • Your deployment pipeline is not mature enough to handle 10+ independently deployable services
ASP.NET Core with a clean layered architecture (Domain → Application → Infrastructure → API) delivers excellent performance, is easy to test, and can handle significant load before you need to reconsider.
The Modular Monolith: The Best of Both Worlds
Between a traditional monolith and full microservices sits the modular monolith — and it is often the architecture we recommend for mid-sized enterprise .NET projects.
A modular monolith organises code into independently deployable modules within a single process. Each module owns its domain, its database schema, and its API surface — but they communicate in-process rather than over the network. When you eventually need to extract a service, the boundaries are already clean.
This approach using .NET 8 with vertical slice architecture, MediatR, and separate EF Core DbContexts per module is our most commonly recommended starting architecture for new enterprise .NET projects in 2025.
When Microservices Are Genuinely the Right Choice
Microservices earn their complexity when you have:
• Independent scaling requirements — your payment service needs 20x more compute than your reporting service • Multiple teams working on the same product who need true deployment independence • Different technology requirements per domain (one service needs ML inference, another needs low-latency caching) • A mature DevOps platform — Azure Kubernetes Service, Azure DevOps pipelines, and distributed tracing already in place • Clear, stable domain boundaries validated over time
Without these conditions, you are paying the microservices tax — network latency, distributed transactions, complex deployments, and operational overhead — without receiving the benefits.
Our Decision Framework
At VFL Technologies we use a simple scoring matrix with clients. Score your project 1–3 on each dimension: team size, domain clarity, scaling requirements, DevOps maturity, and deployment independence needs.
Score under 8: Start with a modular monolith. Score 8–12: Consider microservices for two or three core domains only. Score above 12: Full microservices architecture on Azure Kubernetes Service is justified.
The key insight is that architecture is not a one-time decision. We build modular monoliths designed to be decomposed — so when microservices become the right answer, the migration is evolution, not a rewrite.