Mono Repos
Structure, Benefits & Best
Practices.
April 07, 2025
Dinesh Kumar
VP Engineering @ RadiansysIntroduction
Managing multiple projects efficiently is a common challenge in software development. Traditionally, teams have relied on multi-repository (multi-repo) setups, where each project, library, or service has its own repository. However, an increasing number of organizations are transitioning to mono-repository (mono-repo) structures to enhance collaboration, improve development efficiency, and streamline project management.
What is a Mono Repo?
A mono-repo (monolithic repository) is a single repository that contains multiple projects, services, or packages that belong to the same organization or development ecosystem. Instead of creating separate repositories for different projects, everything is stored in a single repository with a well-organized structure.
Mono Repo vs. Multi Repo
Mono Repo | Multi Repo | |
|---|---|---|
| Code Organization | Single repository for all projects | Separate repositories for each project |
| Versioning | Unified versioning across all services | Different versions in different repos |
| Code Sharing | Easier sharing via internal libraries | Need to publish shared code separately |
| Collaboration | Easier cross-team collaboration | Requires coordination across multiple repos |
| CI/CD Complexity | More complex due to interdependencies | Simpler for independent projects |
Why Choose a Mono Repo?
Enhanced Code Sharing & Reusability
A key advantage of a mono-repo is the ability to seamlessly share libraries, utilities, and components across multiple projects. Instead of maintaining and publishing separate versions for different repositories, developers can directly reference shared code within the same repository. This eliminates redundant code, improves maintainability, and ensures consistency across services.
Atomic and Consistent Changes
With all related projects housed in a single repository, developers can make atomic changes that affect multiple projects simultaneously. This means that when a library, API, or shared component is updated, all dependent services are updated in a single commit. This reduces compatibility issues, minimizes dependency mismatches, and ensures system-wide consistency.
Simplified Dependency Management
Managing dependencies is significantly easier in a mono-repo since all packages and services are contained in one place. Instead of handling separate dependency versions across multiple repositories, teams can use tools like Nx, Lerna, Turborepo, or Bazel to efficiently manage dependencies, optimize builds, and reduce version conflicts. This makes package upgrades and maintenance more predictable and less error-prone.
Streamlined CI/CD Workflows
A mono-repo enables centralized and unified CI/CD pipelines, making it easier to test, build, and deploy changes across different services in a coordinated manner. Teams can implement incremental builds, ensuring that only modified services are rebuilt and tested, thereby reducing execution time and computational costs. Automation tools can intelligently detect affected areas and trigger relevant workflows, enhancing overall efficiency.
Unified Development and Onboarding Experience
Working within a single repository provides a standardized development environment for all teams. New engineers can onboard quickly since they don't need to navigate multiple repositories with different configurations. Development guidelines, tooling, and best practices are consistently applied across the entire codebase, reducing friction and improving productivity.
Greater Code Visibility & Cross-Team Collaboration
Since all code resides in one place, it is easier for review, track changes, and collaborate on different parts of the codebase. Developers can understand interdependencies, contribute to shared modules, and resolve issues more effectively. This transparency fosters a culture of knowledge-sharing and collaboration, which is particularly beneficial for large organizations with multiple teams working on interconnected projects.
Considerations for Scaling a Monorepo
While monorepos provide significant benefits, managing them effectively requires thoughtful strategies and best practices.
As the repository grows, teams should be aware of certain aspects to optimize performance, collaboration, and efficiency.
Scaling Git Performance Efficiently
A growing monorepo naturally accumulates a larger commit history and more files, which can lead to longer operations for cloning and fetching. To ensure a smooth developer experience, teams can leverage techniques like partial clones, shallow clones, and Git LFS to streamline performance without compromising access to necessary code.
Optimizing CI/CD Workflows
Given the interconnected nature of services in a monorepo, CI/CD pipelines should be designed to execute only relevant builds and tests instead of re-running all workflows. Advanced tools such as Bazel, Nx, and GitHub Actions matrix builds help optimize execution by identifying and triggering processes only for affected services, significantly improving build efficiency.
Implementing Fine-Grained Access Control
Monorepos encourage cross-team collaboration, but in some cases, organizations may need to restrict modifications to specific areas of the codebase. Using CODEOWNERS files, directory-based permissions, and Git-based access models ensures structured ownership while maintaining the flexibility of a shared repository.
Managing Parallel Development & Code Synchronization
With multiple teams working on shared components, strategic coordination is key to reducing merge conflicts and ensuring smooth integration. Adopting feature branching, trunk-based development, and automated conflict resolution tools helps teams collaborate effectively while maintaining code stability.
Use a Mono Repo Management Tool
Best Practices for Managing a Mono Repo
Several tools help in managing a mono-repo efficiently
- Nx (for TypeScript/JavaScript projects)
- Lerna (for JavaScript projects)
- Turborepo (for high-performance builds)
- Bazel (Google's build system for large-scale projects)
- Pants (for Python-based mono-repos)
Define a Clear Folder Structure
When setting up a mono-repo, it's important to have a clear and scalable folder structure that promotes collaboration, reusability, and easy maintenance. Organizing your repository with a well-thought-out structure allows different teams to focus on specific parts of the project while ensuring common code is shared seamlessly.
Below is an example of an effective folder structure for a mono-repo setup:
Optimize CI/CD Pipelines
- Use incremental builds to avoid running all tests unnecessarily.
- Use dependency graphs to determine which projects need rebuilding.
- Parallelize builds for improved performance.
Adopt Code Owners and Access Control
Use GitHub's CODEOWNERS file to define code ownership and restrict changes to specific directories.
Use Feature Branching and Trunk-Based Development
Encourage feature branching and frequent merges to avoid large, conflicting changes.
Enforce Code Quality and Testing
- Use linting and formatting tools (ESLint, Prettier, etc.).
- Implement unit, integration, and end-to-end tests to ensure stability.
- Require code reviews before merging changes.
Best Practices for Managing a Mono Repo
Several tools help in managing a mono-repo efficiently
- Nx (for TypeScript/JavaScript projects)
- Lerna (for JavaScript projects)
- Turborepo (for high-performance builds)
- Bazel (Google's build system for large-scale projects)
- Pants (for Python-based mono-repos)
Define a Clear Folder Structure
When setting up a mono-repo, it's important to have a clear and scalable folder structure that promotes collaboration, reusability, and easy maintenance. Organizing your repository with a well-thought-out structure allows different teams to focus on specific parts of the project while ensuring common code is shared seamlessly. Below is an example of an effective folder structure for a mono-repo setup:
Optimize CI/CD Pipelines
- Use incremental builds to avoid running all tests unnecessarily.
- Use dependency graphs to determine which projects need rebuilding.
- Parallelize builds for improved performance.
Adopt Code Owners and Access Control
Use GitHub's CODEOWNERS file to define code ownership and restrict changes to specific directories.
Use Feature Branching and Trunk-Based Development
Encourage feature branching and frequent merges to avoid large, conflicting changes.
Enforce Code Quality and Testing
- Use linting and formatting tools (ESLint, Prettier, etc.).
- Implement unit, integration, and end-to-end tests to ensure stability.
- Require code reviews before merging changes.
When Should You Use a Mono Repo?
Best suited for
Large organizations with multiple interconnected projects.
Teams that heavily share code across services.
Companies that want a unified CI/CD pipeline.
Developers working on modular architectures like microservices.
When to avoid
If your projects are completely independent and rarely share code.
If your team lacks the infrastructure to handle large repositories efficiently.
If Git performance starts becoming a bottleneck.
Conclusion
Mono-repos offer a powerful way to manage multiple projects within a single repository. They improve collaboration, code sharing, and CI/CD workflows , but they also introduce challenges such as scalability, merge conflicts, and access control.
By following best practices, using the right tooling, and structuring your code properly, you can make the most of a mono-repo and ensure smooth development across your teams.
If you're starting fresh or considering migrating to a mono-repo, evaluate your team's needs, infrastructure, and growth plans before making the decision.