What is a Modular Monolith?

A modular monolith is an architectural approach that combines the simplicity of a monolithic application with the modularity of microservices. It structures an application into independent, well-defined modules while maintaining a single deployable unit. This approach reduces operational complexity, improves maintainability, and allows for future scalability—making it ideal for startups and teams needing rapid development without premature microservices overhead.

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2. Core Technical Concepts & Technologies

• Monolithic Architecture (single deployable unit)
• Modular Monolith (logically separated modules within a monolith)
• Domain-Driven Design (DDD) (bounded contexts, encapsulation)
• API Contracts (well-defined interfaces for module communication)
• Evolutionary Architecture (gradual transition to microservices if needed)

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3. Main Points

• Monolithic Architecture

  • All components (UI, business logic, database) are tightly coupled in a single deployable unit.
  • Simple to start but can become unwieldy ("big ball of mud") as complexity grows.

• Modular Monolith

  • Structured into independent modules (e.g., Orders, Payments, Inventory).
  • Clear boundaries via APIs, avoiding tight coupling.
  • **Single database