Software architecture often swings between centralisation and decentralisation. Monorepos house multiple projects in a single repository, while microservices break applications into independent services. Finding the right balance between them is key to developer productivity and system reliability. This article explores the pros and cons of each and how modern tooling helps teams integrate both approaches.

Table of Contents

• 1. What Are Monorepos and Microservices?
• 2. Benefits and Challenges of Monorepos
• 3. Microservices and Polyrepos
• 4. Tools and Practices to Bridge the Gap
• 5. Conclusion

1. What Are Monorepos and Microservices?

A monorepo is a single repository that contains multiple projects or packages. These projects often share tooling, dependencies and infrastructure. Microservices is an architectural style where an application is built as a suite of small services, each running in its own process and communicating over the network. Microservices enable independent deployment and scaling but can be stored in separate repositories (polyrepo) or grouped together in a monorepo.

2. Benefits and Challenges of Monorepos

Monorepos promote code sharing and visibility. You can change an API contract and update all consumers in a single commit. Unified tooling (linters, build scripts) reduces duplication. Dependency management is simpler when versions are aligned.

Challenges include repository size, build performance and permission management. Large monorepos can become unwieldy without good tooling. Build tools like Bazel, Pants and Nx tackle these problems with incremental builds and caching. They know which projects depend on which and rebuild only what changed.

3. Microservices and Polyrepos

Microservices encourage autonomy: each service can be written in different languages, scaled independently and deployed on its own schedule. This works well for large teams that need isolation. A polyrepo—separate repository per service—enforces this independence. However, it can make cross‑cutting changes painful and increase duplication of configuration.

Using a monorepo for microservices combines the best of both worlds. Services remain separate at runtime but live together in one codebase. You gain visibility and can perform atomic cross‑service updates, while still deploying services independently.

4. Tools and Practices to Bridge the Gap

Modern build systems and package managers make managing large monorepos easier. Nx and Turborepo provide task caching and distributed builds; Yarn and pnpm support workspaces that hoist dependencies. You can enforce boundaries with lint rules so that services communicate only through defined interfaces.

DevOps practices like CI/CD pipelines, automated testing and monitoring must scale to many services. Container orchestration platforms like Kubernetes or serverless functions can host microservices irrespective of repository layout. The key is to balance autonomy with cohesion: use monorepos for shared libraries and configuration, and microservices for deployment and runtime isolation.

5. Conclusion

Monorepos and microservices are not mutually exclusive; they are tools you can combine to optimise your workflow. Monorepos improve collaboration and consistency, while microservices provide scalability and independence. With modern tools like Nx, Bazel and Turborepo, you can manage a fleet of services in a single repo and deploy them independently. Evaluate your team’s size, deployment frequency and cross‑service coupling to find the balance that works best for you.