A monolithic application is a single, unified codebase where all components (UI, business logic, database, etc.) are tightly integrated and deployed as one unit.
* Single codebase & repository
* Single deployment unit
* Shared database
* Components are interdependent
* Simpler CI/CD pipelines (single deployment process)
* Easier to test as a whole
* Slow deployments (small changes require full redeployment)
* Scalability issues (entire app must scale together)
* Build: Compile the entire application
* Test: Run unit & integration tests
* Deploy: Deploy the full application
Example: A Java Spring Boot app deployed as a single .jar file.
A microservices application consists of multiple independent services, each handling a specific function and communicating via APIs.
* Independent, loosely coupled services
* Each service has its own database
* Can be developed, tested, and deployed independently
* Uses APIs (REST, GraphQL, gRPC) for communication
* Faster deployments (deploy only the changed service)
* Scalability (scale individual services as needed)
* Technology flexibility (each service can use different tech stacks)
* Complex CI/CD pipelines (each service has its own pipeline)
* Difficult testing (requires API and integration testing)
* Build each microservice separately
* Test each microservice independently
* Deploy each service independently
Example: A Node.js microservice deployed in a Docker container using Kubernetes.
| Feature | Monolithic | Microservices |
|---|---|---|
| Codebase | Single repository | Multiple repositories |
| Deployment | Entire application redeployed | Deploy services independently |
| Scalability | Difficult (must scale the whole app) | Easy (scale individual services) |
| CI/CD Complexity | Simple (one pipeline) | Complex (multiple pipelines) |
| Testing | Easier (single test suite) | Harder (requires API & integration testing) |
| Technology Stack | Single tech stack | Multiple tech stacks |