Why Monolithic Apps Fail: Key Drawbacks That Drive the Shift to Microservices

Monolithic applications have several inherent problems that make them difficult to adapt to modern development demands, leading many teams to consider microservice architectures.

1. Project Over‑Complexity

Simple projects start quickly, but as requirements expand (e.g., building an e‑commerce platform), the single codebase becomes tangled, hard to understand, and increasingly difficult to maintain.

2. Slow Development Speed

When a monolith grows large, every build, test, or run requires the entire project to be compiled and executed, causing long feedback loops; even small changes force a full rebuild.

3. Poor Scalability

Different modules have varying performance needs—some require large memory for Redis caching, others need strong CPU for image processing—yet a monolithic deployment forces all modules onto the same server, meeting the highest requirement for every component.

4. Rigid Technology Stack

Choosing a single technology stack early makes it hard to switch later; legacy codebases become difficult to modernize, and introducing new languages (e.g., Go for high‑concurrency services) is often impossible.

Former Advantages of Monolithic Apps

Simple development: a single IDE can quickly build the whole application.

Easy testing: the entire system can be tested as one unit.

Straightforward deployment: after installing Tomcat, the app can be deployed directly.

Simple clustering: multiple Tomcat instances plus an Nginx can form a cluster quickly.

Despite these benefits, the drawbacks usually outweigh the advantages, especially for larger projects. For small CRUD applications, a monolith may still be appropriate, but for complex systems microservices provide a better solution.

The article concludes by summarizing the problems of monolithic applications and sets up the next piece, which will discuss the advantages of microservices.

Reference: Chris Richardson, Microservices Architecture Design Patterns , Mechanical Industry Press, 2019.