As software systems grow, teams typically oscillate between two extremes: sprawling multi-repo architectures where shared types drift out of sync, or unmaintainable monoliths where tight coupling paralyzes deployments. Monorepos powered by tools like Nx provide a balanced middle ground.

Domain-Driven Project Architecture

In an Nx workspace, applications are thin deployment containers, while core logic lives inside isolated libraries:

apps/
  portfolio-web/
  blog-web/
  api-service/
libs/
  shared/
    types/
    ui-components/
    validations/
  domains/
    billing/
    auth/
    content/

Every library should adhere to strict categorization:

1. Feature: Composed screens and domain behaviors.
2. UI: Pure presentational primitives with zero side effects.
3. Data-Access: API clients, repositories, and state management.
4. Util: Pure helper functions, formatting, and mathematical utilities.

Module Boundary Enforcement

To prevent architectural entropy, Nx allows tagging libraries and enforcing boundary constraints via ESLint:

{
  "rules": {
    "@nx/enforce-module-boundaries": [
      "error",
      {
        "depConstraints": [
          { "sourceTag": "scope:blog", "onlyDependOnLibsWithTags": ["scope:blog", "scope:shared"] },
          { "sourceTag": "type:ui", "onlyDependOnLibsWithTags": ["type:util", "type:ui"] }
        ]
      }
    ]
  }
}

This ensures that presentation components can never directly import database models or domain controllers.

Computation Caching: The Speed Multiplier

Nx tracks source code hashes, dependencies, and environment variables to construct an execution graph. When executing tasks:

nx run-many -t test build --parallel

If a library and its dependencies have not changed, Nx restores outputs from the local or cloud cache instantaneously: [existing outputs match the cache, skipping execution].

Conclusion

Adopting an Nx monorepo brings structural discipline, unified TypeScript typings, and near-instant local build feedback loops to modern development teams.