For years, the software industry has been brainwashed by a pervasive mindset: “A Modular Monolith is just a weak stepping stone before the system gets big enough to graduate to Microservices.” Countless companies, even those with engineering teams you can count on two hands, rushed to dismantle their monoliths to chase the distributed “cloud” dream.

They called it the Future. Architect Rico Fritzsche calls it “CV-Driven Development” in his famous GitConnected article. And the hard data from 2025 is proving Rico right.

1. The Receding Tide of Microservices (Hard Data)

According to a 2025 CNCF survey, 42% of organizations that adopted Microservices have consolidated their systems back into Modular Monoliths after hitting the “Coordination Ceiling,” where operational costs choke technical benefits.

If you still believe Microservices are the undeniable pinnacle of architecture, look at the most dramatic “U-turns” in the industry:

Amazon Prime Video: 90% Cost Savings

In early 2023, Amazon Prime Video shocked the tech world by abandoning their Serverless Microservices architecture (AWS Lambda/Step Functions) for their Video monitoring system. The reason? Millions of state transitions and constant network data transfers via S3 created massive latency and an astronomical AWS bill. By consolidating everything into a single Monolith running on EC2/ECS, they reduced infrastructure costs by 90%.

Segment: Goodbye 140 Microservices

Segment once sliced their system into 140 independent Microservices. Instead of shipping new features, their engineers were forced to become “plumbers”—configuring Service Meshes, managing cross-dependencies, and desperately trying to trace bugs across dozens of repositories (massive Cognitive Load). When they consolidated back into a Modular Monolith, their deployment velocity skyrocketed.

2. Anatomy of the “Distributed Monolith” Trap

The Distributed Monolith is a disastrous anti-pattern where a system is split into multiple services that remain tightly coupled, forcing you to inherit all the drawbacks of Microservices with none of the benefits.

Imagine splitting an E-commerce system into OrderService, PaymentService, and InventoryService. When a new order arrives, Order makes a gRPC call to Payment, waiting for Payment to make an HTTP call to Inventory.

graph TD
    subgraph Distributed_Monolith ["The Distributed Monolith Anti-Pattern"]
        Order[Order Service]
        Payment[Payment Service]
        Inventory[Inventory Service]
        
        Order -- HTTP / Tightly Coupled --> Payment
        Payment -- gRPC / Tightly Coupled --> Inventory
        Inventory -- Timeout / Fail --> Payment
        Payment -- Cascading Failure --> Order
    end
    
    style Order fill:#f9c,stroke:#333
    style Payment fill:#f9c,stroke:#333
    style Inventory fill:#f9c,stroke:#333
  • The Distributed Penalty: An in-memory function call takes a few nanoseconds. A network call between two services takes several milliseconds (millions of times slower).
  • No Independent Deployment: If you change the data schema in Order, the Payment service crashes.
  • Complex Transactions: You are forced to implement complex distributed transaction patterns like Sagas or Two-Phase Commits (2PC).

3. Why Golang Was Born for Modular Monoliths

Golang provides powerful code isolation mechanisms (like internal packages) and native in-memory communication (Go Channels, Interfaces), making it the ultimate language for designing ultra-low latency Modular Monoliths.

Instead of relying on Kubernetes namespaces and gRPC to isolate modules, Golang allows you to enforce boundaries directly at the Compiler level.

Isolating Domains with internal packages

Go has an elegant feature: the internal/ directory. Code placed inside internal/ can only be accessed by packages sharing the same parent directory. You can break tight coupling without having to split code into separate repositories.

project-root/
├── cmd/
│   └── api/
│       └── main.go (Single Entrypoint - 1 Binary)
├── internal/
│   ├── order/
│   │   ├── handler.go
│   │   └── service.go (Communicates with payment strictly via Interface)
│   ├── payment/
│   │   └── service.go

In-Memory Communication

Instead of Order firing an HTTP request to Payment, they communicate via Interfaces (Dependency Injection) or by passing Events through Go Channels. Everything happens inside a single OS Process, within shared RAM. The speed is measured in nanoseconds. Even if you eventually need to decouple, refer to Building Event-Driven Microservices with NATS to avoid synchronous HTTP calls.

4. Conway’s Law: When Do You Actually Need Microservices?

Conway’s Law states: “Organizations which design systems are constrained to produce designs which are copies of the communication structures of these organizations.”

You should only adopt Microservices when you meet these conditions:

  1. Organizational Scale: You have >50 Backend Developers, split into independent “2-pizza” teams (5-7 people). Merging code into a single repository causes conflicts that CI/CD can no longer resolve efficiently.
  2. Asymmetrical Infrastructure Scaling: For instance, a “Video Encode” feature requires GPUs and consumes 90% CPU, while the “User Profile” feature only needs RAM. In this scenario, extracting VideoService into its own deployment unit makes practical sense.

Frequently Asked Questions (FAQ)

1. What is the “Coordination Ceiling”? It is the threshold where the operational costs of maintaining a distributed system (network latency, data consistency, CI/CD pipeline complexity) officially exceed the benefits of independent deployment. Past this ceiling, Microservices become a financial and operational burden.

2. How do you scale a Modular Monolith? Horizontal Scaling! You can simply run 50 containers (or EC2 instances) of the exact same Modular Monolith source code behind a Load Balancer. You do not need Microservices to scale horizontally.

3. How do you prevent Spaghetti Code in a Monolith? Adopt Hexagonal Architecture or Clean Architecture. Use Dependency Injection and force modules to communicate exclusively through defined Interfaces. In Golang, aggressively use internal/ packages so the Compiler automatically blocks illegal cross-module access.

Conclusion

A Modular Monolith is not an outdated predecessor to Microservices. It is a complete, highly optimized destination. Build a clean Modular Monolith with strict Domain boundaries. Only carve it up into Microservices if—and only if—the cost of communication between humans (Developers) becomes higher than the cost of communication over the Network.