Microservices vs Monolith: Making the Right Choice

Introduction

“Should we use microservices?” is one of the most common architecture questions I get asked. The answer is almost always “it depends,” but that’s not helpful. This article provides a concrete framework for making this decision.

The Honest Truth

Most teams that adopt microservices too early regret it. The complexity overhead is significant, and the benefits only materialize at certain scales.

I’ve seen:

• A 5-person startup with 20 microservices struggling to ship features
• A 200-person company with a well-structured monolith moving faster than competitors

The architecture should match your context, not your aspirations.

When Monoliths Win

Small to Medium Teams (< 50 engineers)

With a smaller team:

• Communication overhead is low
• Shared code ownership works
• Deployment coordination is manageable
• You can’t afford the operational overhead of distributed systems

Early-Stage Products

When you’re still figuring out:

• What features users want
• Where the domain boundaries are
• What the performance requirements are

A monolith lets you iterate faster and refactor easily.

Simple Domains

If your business logic is straightforward and doesn’t have natural boundaries, forcing microservices creates artificial complexity.

When Microservices Win

Large Teams (50+ engineers)

At scale:

• Teams need autonomy to move fast
• Deployment coordination becomes a bottleneck
• Different parts of the system have different scaling needs

Clear Domain Boundaries

When you have:

• Distinct business capabilities (payments, inventory, shipping)
• Different data ownership requirements
• Teams aligned to business domains

Different Technical Requirements

When parts of your system need:

• Different languages or frameworks
• Different scaling characteristics
• Different deployment frequencies
• Different reliability requirements

The Decision Framework

Score your situation on these factors:

Team Size and Structure

Domain Complexity

Deployment Needs

Scaling Requirements

Interpretation:

• Score > 3: Strong monolith candidate
• Score -2 to 3: Either works, consider team preference
• Score < -2: Strong microservices candidate

The Modular Monolith: Best of Both Worlds

Before jumping to microservices, consider a modular monolith:

src/
├── modules/
│   ├── users/
│   │   ├── api/
│   │   ├── domain/
│   │   └── infrastructure/
│   ├── orders/
│   │   ├── api/
│   │   ├── domain/
│   │   └── infrastructure/
│   └── payments/
│       ├── api/
│       ├── domain/
│       └── infrastructure/
└── shared/
    └── kernel/

Benefits:

• Clear boundaries without network overhead
• Easy to extract to services later
• Single deployment, simpler operations
• Enforced module boundaries through code structure

Migration Path

If you start with a monolith and need to migrate:

1. Identify Extraction Candidates

Look for modules that:

• Have clear boundaries
• Need independent scaling
• Have different deployment needs
• Are owned by a specific team

2. Strangler Fig Pattern

Don’t rewrite—gradually extract:

1. Put a facade in front of the monolith
2. Extract one capability to a service
3. Route traffic to the new service
4. Repeat

3. Start with the Edges

Extract services that:

• Have fewer dependencies
• Are less critical (lower risk)
• Have clear interfaces

Common Mistakes

Premature Decomposition

Splitting before you understand the domain leads to wrong boundaries. It’s much harder to merge services than to split a monolith.

Distributed Monolith

If your services:

• Must be deployed together
• Share a database
• Have synchronous dependencies everywhere

You have a distributed monolith—all the complexity, none of the benefits.

Ignoring Operational Costs

Microservices require:

• Service discovery
• Distributed tracing
• Log aggregation
• Container orchestration
• More on-call complexity

Make sure you can afford this overhead.

Real-World Example

A company I advised had 30 engineers and 15 microservices. They were struggling with:

• Slow feature development (changes touched multiple services)
• Frequent integration issues
• Complex deployment coordination
• High operational overhead

We consolidated to 4 services aligned with team boundaries:

• Core platform (shared)
• Customer-facing product
• Internal tools
• Data pipeline

Result:

• 40% faster feature delivery
• 60% fewer production incidents
• Happier engineers

Conclusion

The microservices vs monolith debate isn’t about which is “better”—it’s about which fits your context.

Start with a well-structured monolith. Add clear module boundaries. Extract to services only when you have a concrete reason: team autonomy, independent scaling, or different technical requirements.

The best architecture is the one that lets your team ship value to users quickly and reliably. Sometimes that’s microservices. Often, it’s not.