.NET Architecture & System Design Interview Question #102

What is a modular monolith?

Microservices, API Gateway, Service Communication & Event-Driven Architecture Mid-Level Intermediate

Quick Interview Answer

A modular monolith is a single deployable application divided into well-defined business modules with controlled dependencies and explicit contracts.

Detailed Explanation

A modular monolith is a single deployable application divided into well-defined business modules with controlled dependencies and explicit contracts.

It preserves the operational simplicity of one deployment while improving maintainability and domain separation. Strong module boundaries also make it easier to extract a module into a separate service later if a genuine need appears.

Code Example

Application
  |- Orders Module
  |- Billing Module
  |- Inventory Module
  |- Identity Module

One deployment
Explicit module boundaries