Monolithic Architecture
A monolith packages the entire application—database writes, frontend logic, notification templates, payment runs—into a single deployable code bundle. Monoliths are easy to deploy, simple to test, and have zero network latency between modules. However, as teams grow, code changes can conflict and deploy times slow down.
Microservices: Distributed Isolation
Microservices split the application into separate services that run independently and communicate over network APIs (HTTP, gRPC, queues). This allows modules to be scaled separately and written in different languages. However, it introduces complex deployment requirements, database consistency concerns, and network reliability issues.
The Modular Monolith Middle Ground
A modular monolith keeps a single codebase and database, but strictly enforces code boundaries between modules using interfaces. This provides the simplicity of a monolith with the boundary isolation of microservices, allowing for easy migration to microservices later.