How to architect large-scale Angular apps with Nx & modules?

Long Answer

When building a large-scale Angular application, architecture must balance scalability, maintainability, and performance. Patterns like Nx monorepos, standalone components, and feature modules help achieve modular growth while avoiding tangled dependencies.

1) Monorepo with Nx for orchestration

‍Nx provides tooling to structure apps and libraries in a monorepo. Applications and libraries live in apps/ and libs/. Libraries can represent domains (auth, payments, dashboard), shared UI, or utility services. Nx automatically caches builds and test results, enabling incremental builds—only changed libraries are rebuilt. This reduces CI/CD time and makes large projects manageable. Dependency graphs enforce boundaries: feature libs cannot import from other domains directly, only through defined public APIs.

2) Standalone components for flexibility

‍Angular’s standalone components reduce NgModule overhead. By declaring components as standalone and importing dependencies directly, bootstrapping becomes faster and more granular. Shared UI elements (buttons, modals) can be authored as standalone and consumed across domains. This simplifies testing and avoids bloated root modules.

3) Feature modules for domain isolation

‍Each major domain should be isolated into a feature module or library (e.g., feature-orders, feature-users). These modules encapsulate components, services, and routing for that domain. By lazy-loading these modules through Angular’s router, we achieve route-level code splitting, so only code for the active domain is loaded at runtime. This reduces initial bundle size and speeds up first paint.

4) Domain-driven design (DDD) boundaries

‍Domains map to libraries inside Nx:

• Domain libraries: contain business logic for a bounded context (e.g., payments).
  
• Feature libraries: contain UI and routing for user-facing flows.
  
• Shared libraries: hold cross-cutting utilities or components (logging, pipes, design system).
  Nx tags and lint rules enforce these rules: features can depend only on their domain and shared libs; no cross-domain imports allowed. This prevents spaghetti dependencies and keeps the graph clear.
  

5) Routing and code splitting

‍Angular supports lazy-loading modules via the router. In modern Angular, standalone route definitions allow importing standalone components directly. For large apps, each domain’s route points to a lazy-loaded feature module or component. Combined with Nx, CI builds only affected routes after a change. Users download only the code they need, reducing load times and memory footprint.

6) Shared state and services

‍Global state (auth, user profile) is isolated in a core library or service. Domain state is contained within its feature module, often managed with NgRx or signals. This separation prevents state leaks across domains. For async operations, interceptors live in core/http libraries, avoiding duplication.

7) Incremental builds and CI/CD

‍Nx’s affected commands (nx affected:build/test/lint) ensure only changed libraries trigger pipelines. This saves minutes (or hours) in CI. With project graph visualization, developers instantly see which apps/libs depend on a change, reducing regression risks.

8) Governance and documentation

‍Every library has a clear README explaining ownership, boundaries, and dependencies. Automated linting enforces import boundaries. Architectural decisions are codified in Nx workspace.json and lint rules, ensuring consistency even across large teams.

In short, scalable Angular apps combine Nx monorepos for orchestration, standalone components for flexibility, feature modules for encapsulation, and route-level code splitting for performance. Clear domain-driven boundaries enforced by Nx keep growth sustainable while ensuring developer velocity.

Common Mistakes

Common errors include: stuffing too much logic into the app.module.ts, leading to bloated startup bundles. Overusing shared libraries so everything becomes “shared,” eroding domain boundaries. Ignoring Nx lint rules, allowing cross-domain imports that create spaghetti dependencies. Using eager loading for all modules, making initial load slow. Treating standalone components as replacements for all modules instead of strategically applying them. Forgetting to enforce incremental builds in CI, causing long pipelines. Finally, not documenting library ownership, leaving teams confused about which module owns what.

Sample Answers

Junior:

‍“I’d split features into modules, use lazy loading, and keep shared UI in a library. Standalone components simplify reusable widgets.”

Mid:

‍“I’d organize code in an Nx monorepo, separating features, domains, and shared libs. Feature modules lazy-load for route-level splitting. Standalone components cover design system elements. CI uses Nx affected builds for speed.”

Senior:

‍“I’d adopt Nx for monorepo governance with tags and lint rules. Each bounded context is a domain lib; features encapsulate routing/UI and lazy-load per route. Standalone components improve modularity and bootstrap time. Core libraries manage global concerns. Incremental builds with Nx reduce CI cost. Clear ownership + dependency graphs enforce domain boundaries and prevent leakage. This yields scalable, resilient architecture that evolves with business needs.”

Evaluation Criteria

Interviewers look for structured thinking:

• Use of Nx monorepo for orchestration and incremental builds.
  
• Feature modules + lazy loading for encapsulation and splitting.
  
• Standalone components for reusable UI and smaller bootstraps.
  
• Clear domain boundaries via domain libs + lint rules.
  
• Governance: READMEs, ownership, dependency tagging.
  
• CI/CD efficiency: nx affected commands, cached builds.
  
• Awareness of pitfalls: over-shared libs, bloated modules, cross-import leaks.
  Strong answers tie design to outcomes: faster builds, smaller bundles, modular team ownership. Weak answers focus only on modules or only on lazy loading without addressing maintainability or scalability.
  

Preparation Tips

Practice by creating a dummy Nx workspace with two apps (admin, shop) and libraries (feature-checkout, domain-orders, ui-buttons). Configure tags in nx.json to block cross-domain imports. Write a standalone component (modal) and consume it in a feature lib. Add lazy loading to routes (loadChildren/standalone imports). Run nx graph to visualize dependencies. Use nx affected:build to see incremental builds in action. Study Angular’s guide on standalone APIs and Nx docs on workspace layout. Practice a 60s pitch: monorepo with Nx, domain-driven libs, feature modules for lazy loading, standalone components for reusability, and incremental builds for CI/CD efficiency.

Real-world Context

A fintech firm with multiple apps (admin, dashboard, customer portal) used Nx monorepos to unify builds. Domains like payments and onboarding became separate libraries, isolating logic and preventing leaks. Standalone UI components built a consistent design system. Route-level lazy loading cut initial bundle size by 40%. Incremental builds reduced CI time from 30 minutes to under 7. Another SaaS platform scaled from 5 to 50 developers: Nx dependency graphs enforced domain boundaries, preventing cross-import chaos. These real-world results show that structured Angular architecture with Nx, standalone components, and feature modules scales both code and teams effectively.

Key Takeaways

• Nx monorepos enable incremental builds + dependency enforcement.
  
• Feature modules + lazy loading = route-level code splitting.
  
• Standalone components simplify reusable UI.
  
• Domain libs enforce boundaries and avoid spaghetti code.
  
• CI/CD efficiency and governance are key to long-term scalability.
  
  

Practice Exercise

Scenario: You’re leading a team building an Angular platform with admin, client, and partner portals. The app will grow to 200+ components and must support multiple squads working in parallel.

Tasks:

1. Create an Nx workspace with apps/ for portals and libs/ for domains/features.
   
2. Define domain-users, domain-payments, and domain-reports libraries. Add feature-profile and feature-checkout.
   
3. Build a ui-buttons library with standalone components; consume across features.
   
4. Configure nx.json tags: features may depend on their domain + UI only.
   
5. Add lazy loading for routes: /profile → feature-profile, /checkout → feature-checkout.
   
6. Implement incremental builds with nx affected:build. Break a domain service and watch CI rebuild only affected apps/libs.
   
7. Document ownership in each lib’s README.
   

Exercise: In 60–90s, explain: Nx monorepo orchestration, standalone components, feature modules for lazy loading, domain libs for boundaries, and incremental builds for speed. Show how this scales as more portals and teams join.