A monorepo does not need a complex tool from day one. The key is distinguishing where projects live, how they share dependencies, and who decides which tasks should run.

Introduction

When an application grows, several projects appear: frontend, API, shared libraries, internal tools, and tests. We can keep them in separate repositories or group them in a single repository: a monorepo.

This is where confusion often appears: Bun Workspaces, pnpm Workspaces, and Nx are compared as if they did exactly the same thing. In reality, they operate at different layers:

• Monorepo is a strategy for organizing source code.
• Workspaces let you manage related packages inside a repository.
• Bun and pnpm install dependencies, link local packages, and run scripts.
• Nx coordinates projects and tasks, identifies affected projects, and reuses results through caching.

That is why you do not always have to pick one of the three. A combination such as pnpm + Nx or Bun + Nx can make sense: the package manager and the orchestrator solve different problems.

The question is not which tool wins in the abstract, but how much coordination the repository needs and what complexity is worth taking on.

1. What is a monorepo and why does it exist?

A monorepo contains several projects or packages in a single Git repository. It does not mean everything is one application, or that every project must deploy together.

unio/
├── apps/
│   ├── web/
│   ├── api/
│   └── admin/
├── packages/
│   ├── ui/
│   ├── contracts/
│   ├── config/
│   └── utils/
├── package.json
└── README.md

Applications can deploy separately while sharing libraries and conventions.

Advantages

• Coordinated changes: update a library and its consumers in the same commit.
• Visible shared code: contracts, components, and utilities live close to their consumers.
• Consistent configuration: linting, TypeScript, tests, and conventions can be centralized.
• Cross-cutting refactors: it is easier to adapt several projects to a contract change.
• Less friction with internal dependencies: packages can be referenced as workspaces.

Disadvantages

• Larger repository: cloning, indexing, and navigating can cost more.
• Heavier CI: without a task strategy, every change can run unnecessary builds and tests.
• Unclear boundaries: a monorepo does not prevent coupling or circular dependencies.
• Ownership and permissions: teams need to define who maintains each area.
• Heterogeneous deploys: projects with different runtimes, languages, or release processes need extra care.

A monorepo is useful when projects share code, contracts, practices, or change cycles. If they are independent, have very different permissions, and almost never share code, multiple repositories can be simpler.

2. What Workspaces solve

Workspaces let you declare several packages in the same repository and have them depend on each other through package names.

{
  "name": "@acme/web",
  "dependencies": {
    "@acme/ui": "workspace:*"
  }
}

The workspace: protocol expresses that the dependency must resolve against a local package in the monorepo. Each package keeps its own package.json and declares the dependencies it uses.

Workspaces help with:

• Coordinated installation.
• Linking local packages.
• A lockfile to reproduce the install.
• Running scripts across several packages.
• Managing internal dependencies.

But a workspace alone is not necessarily a complete build system. It can run scripts, but it does not always know which projects were affected by a change or which artifacts it can restore from a cache.

3. Bun Workspaces: simplicity within the Bun ecosystem

Bun supports workspaces through the workspaces field in package.json.

{
  "name": "acme",
  "private": true,
  "workspaces": ["apps/*", "packages/*"]
}

Internal packages can depend on each other with workspace:*. Bun lets you install dependencies from the root and run scripts with filters.

Advantages

• Direct integration with Bun.
• Familiar configuration through package.json.
• Installing and linking internal packages.
• Filters to install or run scripts in selected packages.
• A lightweight solution for small and medium projects.

Disadvantages and limits

• Workspaces alone do not replace a full orchestrator.
• Selecting affected projects and caching builds require other capabilities or tools.
• It is worth validating compatibility with CI, publishing, bundlers, and deploy.
• Tools that expect a specific lockfile or install layout may need adjustments.

When to choose it: if you already use Bun and want to manage local packages with little configuration. If the repository grows and CI repeats expensive work, you can add an orchestrator later.

4. pnpm Workspaces: explicit and efficient dependency management

pnpm lets you organize related projects in a monorepo. The definition usually lives in pnpm-workspace.yaml:

packages:
  - "apps/*"
  - "packages/*"

A project can declare an internal dependency like this:

{
  "name": "@acme/web",
  "dependencies": {
    "@acme/contracts": "workspace:*"
  }
}

pnpm uses a shared content store and links to avoid unnecessary duplication. Its model can reveal dependencies that an application was using without declaring them correctly, which encourages more precise manifests.

Advantages

• Efficient dependency storage management.
• Strong support for local packages and monorepos.
• Explicit workspace: protocol.
• Filters to run tasks in selected packages and their dependencies or dependents.
• An ecosystem widely used in JavaScript and TypeScript.

Disadvantages

• Some older tools assume a flat node_modules layout and may need adjustments.
• The team must learn filter syntax and workspace configuration.
• pnpm manages dependencies and scripts, but a dedicated orchestrator can provide more control over complex graphs and build caching.

When to choose it: if you want a solid base for a JavaScript/TypeScript monorepo with explicit dependencies and useful filters. For many teams, pnpm Workspaces is enough at first; Nx can be added when task coordination justifies it.

5. Nx: understanding and orchestrating the monorepo

Nx plays a different role. It can work on an existing monorepo that uses pnpm, Bun, npm, or Yarn. You do not need to replace the package manager.

Nx builds a project graph and a task graph. It can use the dependencies between applications and libraries to order tasks, identify affected projects, and decide when to reuse a cached result.

Imagine this structure:

apps/
├── web
└── api

packages/
├── ui
├── contracts
└── utils

If you only change api, you may not need to rebuild web. If you change contracts, several consumers may be affected. Nx can use the graph to run the tasks related to the change.

Task cache

When a task is configured as cacheable, Nx computes a fingerprint from its relevant inputs. If those inputs have not changed and a valid result exists, it can restore artifacts and output instead of running the work again.

Remote cache can share results across development machines and CI, depending on configuration and permissions.

Advantages

• Project and dependency graph.
• Ordered task execution.
• Affected project selection with nx affected.
• Local and remote cache.
• Plugins, generators, and integrations.
• Can be added to an existing monorepo without replacing the package manager.

Disadvantages

• Introduces additional concepts and configuration.
• Caching depends on correctly declaring inputs, outputs, and dependencies.
• It can be excessive for a small repository with fast builds.
• Generators and conventions require discipline.
• Remote cache needs extra configuration and may depend on external services depending on the mode.

When to choose it: when there are many applications or libraries, expensive builds, inter-project dependencies, and pipelines that repeat unnecessary work.

Nx does not automatically make business code faster. Its value is in reducing development and CI work and coordinating tasks.

6. Direct comparison

Capability	Bun Workspaces	pnpm Workspaces	Nx
Main role	Dependencies and packages with Bun	Dependencies and packages with pnpm	Orchestration of projects and tasks
Install dependencies	Yes	Yes	Not its main role
Link local packages	Yes	Yes	Uses the existing manager
Run scripts	Yes, with filters	Yes, with filters	Yes, with task pipelines
Project and task graph	Basic relative to its workspace role	Filters based on package relationships	Explicit project and task graph
Affected project selection	Not equivalent to a full affected system	Package filters; change-based flow needs extra setup	Yes, via nx affected
Build cache	Not its main role	Not its main role	Yes
Remote task cache	Requires another tool	Requires another tool	Available with compatible configuration
Initial complexity	Low	Low to moderate	Moderate

The right comparison is not “Bun or pnpm or Nx.” Bun or pnpm can manage dependencies while Nx coordinates which tasks to run and which can be reused.

7. Do I need Nx from day one?

Scenario A: few projects and simple scripts

You have a web app, an API, and a shared library. Builds are fast and CI is simple.

Recommendation: start with Bun Workspaces or pnpm Workspaces. Keep scripts clear and avoid a configuration layer that does not yet provide enough value.

Scenario B: several applications and libraries

You have frontend, backend, admin panel, UI, contracts, and shared utilities. Builds start to take longer and changes affect subsets of projects.

Recommendation: use Bun or pnpm for dependencies and evaluate Nx to coordinate tasks, select affected projects, and cache results.

Scenario C: large monorepo with several teams

There are many applications, libraries, conventions, and pipelines. You need architectural rules, generators, and remote cache.

Recommendation: Nx can add value if the team can maintain its configuration and understands the graph it is using.

Scenario D: multiple languages

If the repository includes Java, Go, Rust, or other technologies, evaluate the real support of each tool and its integration with existing build systems. Do not choose a tool only because of the folder structure.

8. Architectural risks that no tool removes

A monorepo can end up with circular dependencies, direct imports into internal details, and shared libraries that become an excessive coupling point.

Good practices:

• Define responsibilities for each application and library.
• Declare dependencies explicitly.
• Avoid cycles between packages.
• Keep clear public APIs in shared libraries.
• Separate reusable code from application-specific code.
• Define which tasks should run on each change.
• Correctly configure inputs and outputs of cacheable tasks.
• Keep deploys independent when needed.
• Agree on owners, permissions, and release rules.

A monorepo does not mean a single deploy, a single database, or a single application. It is a decision about how to organize and evolve source code.

9. Reference structure

For a platform with several applications and shared packages:

repo/
├── apps/
│   ├── web/
│   ├── api/
│   └── admin/
├── packages/
│   ├── ui/
│   ├── contracts/
│   ├── config/
│   └── utils/
├── package.json
├── pnpm-workspace.yaml
├── nx.json
└── tsconfig.base.json

This structure is a convention, not a requirement. What matters is that dependencies are declared and that build, test, and lint commands are reproducible.

In a small repository you can omit nx.json and start with workspaces only. If you later need orchestration, Nx can be added without requiring you to reorganize everything from scratch.

10. Final decision

Choose Bun Workspaces if you already use Bun and want to manage local packages with little configuration.

Choose pnpm Workspaces if you want a solid base for a JavaScript/TypeScript monorepo, with explicit dependencies and useful filters.

Add Nx if you need to understand inter-project dependencies, run only affected tasks, and take advantage of local or remote cache.

A reasonable strategy is to start with workspaces and add Nx when CI cost and task coordination justify it. For large repositories from the start, it can make sense to bring in Nx earlier if its capabilities meet concrete needs.

Conclusion

The monorepo solves a code-organization problem. Workspaces solve management of related packages. Nx addresses another problem: coordinating projects and tasks intelligently.

Mixing these layers leads to choosing tools by popularity or expecting orchestration capabilities from a package manager that it does not aim to provide.

The best architecture is not the one with the most tools, but the one that keeps dependencies clear, avoids unnecessary work, and remains understandable to the team.

Start with what you need today, measure where costs appear, and add complexity when there is a concrete benefit.

In this series

1. Monorepo: Bun, pnpm, and Nx (this post)
2. Deploys in monorepos

Related reading

• Bun: is it really faster than Node.js?
• Node.js vs Bun vs Deno
• Tool: which runtime suits you

References

• Bun — Workspaces
• Bun — Set up a monorepo with workspaces
• pnpm — Workspaces
• Nx — How Nx Works
• Nx — Caching Tasks
• Nx — Remote Cache
• Nx — Adding Nx to an existing monorepo