Building a Scalable Nx Monorepo Structure for Full-Stack Applications

Building a Scalable Nx Monorepo Structure for Full-Stack Applications

Monorepos have become increasingly popular in modern development for their ability to centralize code, improve collaboration, and simplify dependency management. For full-stack applications, managing both frontend and backend code in a single monorepo can be especially beneficial. Nx, a powerful monorepo tool, allows teams to efficiently manage projects of any size by providing a modular, maintainable structure.

In this article, we’ll explore an advanced folder structure for a full-stack Nx monorepo that includes both frontend and backend applications. This structure is optimized for scalability, reusability, and ease of maintenance.

Why Choose Nx for Full-Stack Monorepos?

Before we dive into the structure, let’s quickly cover the benefits of using Nx for a full-stack monorepo:

1. Shared Libraries: Nx promotes reusability by allowing shared libraries across different applications. This is ideal for managing common code, like UI components, utilities, or business logic.
2. Dependency Graphs and Affected Files: Nx analyzes dependencies to run tasks only on affected code, making CI/CD pipelines faster.
3. Code Consistency: By centralizing configurations and code standards, Nx ensures consistency across applications and teams.

Designing the Folder Structure

Here’s the recommended folder structure for a full-stack Nx monorepo that supports multiple frontend and backend applications.

root
├── apps/
│   ├── frontend/
│   │   ├── web-app/
│   │   │   ├── src/
│   │   │   ├── assets/
│   │   │   ├── environments/
│   │   │   ├── app.config.json
│   │   │   └── ... (e.g., Angular, React, or Next.js app structure)
│   │   ├── mobile-app/
│   │   │   ├── src/
│   │   │   └── ... (e.g., React Native or Expo)
│   ├── backend/
│   │   ├── api/
│   │   │   ├── src/
│   │   │   ├── config/
│   │   │   ├── db/
│   │   │   ├── app.config.json
│   │   │   └── ... (e.g., NestJS, Express, or Fastify structure)
│   │   ├── worker/
│   │   │   ├── src/
│   │   │   └── ... (background workers, queues, etc.)
│   │   └── ...
│   └── ...
├── libs/
│   ├── frontend/
│   │   ├── ui/
│   │   │   ├── src/
│   │   │   └── ... (shared UI components, e.g., React or Angular components)
│   │   ├── state/
│   │   │   ├── src/
│   │   │   └── ... (state management, e.g., Redux, NgRx)
│   │   ├── services/
│   │   │   ├── src/
│   │   │   └── ... (frontend services, e.g., API calls, utils)
│   │   └── ...
│   ├── backend/
│   │   ├── utils/
│   │   │   ├── src/
│   │   │   └── ... (backend utilities, e.g., date formatters, parsers)
│   │   ├── db/
│   │   │   ├── src/
│   │   │   └── ... (database models and services)
│   │   ├── auth/
│   │   │   ├── src/
│   │   │   └── ... (authentication utilities, strategies, middlewares)
│   │   └── ...
│   ├── shared/
│   │   ├── types/
│   │   │   ├── src/
│   │   │   └── ... (TypeScript interfaces, types, shared models)
│   │   ├── constants/
│   │   │   ├── src/
│   │   │   └── ... (shared constants, e.g., API routes, environment variables)
│   │   ├── utils/
│   │   │   ├── src/
│   │   │   └── ... (general-purpose utilities, e.g., date functions)
│   │   └── ...
│   └── ...
├── tools/
│   ├── scripts/
│   │   └── ... (custom scripts, e.g., deployment, migration scripts)
│   ├── generators/
│   │   └── ... (Nx generators to automate library or app creation)
│   └── ...
├── .nx/
├── nx.json
├── tsconfig.base.json
├── workspace.json
└── package.json

Detailed Breakdown

1. apps/ - Applications

This folder contains all applications in the monorepo. Organizing applications into frontend and backend directories makes it easy to distinguish the different types of apps.

• frontend/: Contains web and mobile applications. Each app (web-app, mobile-app) can be structured with subfolders such as src/ for source code, assets/ for static files, and environments/ for configuration files.
• Example: A web-app could be a Next.js application with custom pages, components, and API routes. Similarly, a mobile-app could be a React Native app with shared UI libraries for consistency with the web app.
• backend/: Contains backend applications and services. Typical backend apps might include an api (e.g., NestJS, Express, or Fastify) and potentially a worker service for background jobs and queue processing.
• Example: api could be a NestJS application with modularized services and controllers for handling HTTP requests, while worker might handle background tasks like sending emails or processing data asynchronously.

2. libs/ - Libraries

The libs folder contains all shared code libraries that can be reused across multiple applications, promoting modularity and consistency. Here’s how to organize this section:

• frontend/: Contains frontend-specific libraries, organized by purpose.
• ui/: Shared UI components such as buttons, modals, or form inputs. This library is ideal for components that are reused across web and mobile applications.
• state/: Centralized state management logic, using tools like Redux or NgRx. Centralizing state logic makes it easy to manage state across multiple frontend applications.
• services/: Frontend services for handling API calls, authentication, and other business logic.
• backend/: Contains backend-specific libraries.
• utils/: Backend utilities such as date formatters, parsers, or custom logging functions.
• db/: Database models and services, allowing backend applications to access a shared data layer.
• auth/: Authentication utilities, middlewares, and strategies, which can be reused across multiple backend applications.
• shared/: Contains libraries that are used by both frontend and backend applications.
• types/: TypeScript interfaces and shared models, keeping types consistent across frontend and backend code.
• constants/: Shared constants like API routes or environment variables.
• utils/: General-purpose utilities (e.g., date functions or formatters) that are used across the entire codebase.

3. tools/ - Custom Tools and Scripts

The tools folder is for custom tools and scripts that assist with development, testing, or deployment tasks.

• scripts/: Contains custom scripts for tasks like database migrations, deployments, or running tests.
• generators/: Nx generators can automate the creation of applications or libraries following consistent templates. For example, a generator could scaffold a new backend API module with preconfigured routes, controllers, and services.

Example Use Cases for Shared Libraries

Here are a few practical examples of shared libraries in action:

1. UI Library for Consistency: The libs/frontend/ui library can house reusable UI components that maintain consistent branding and design across the web and mobile apps. A Button component can be developed once and used across multiple applications, ensuring that updates are consistent.
2. Shared Types for API Consistency: The libs/shared/types library can define TypeScript interfaces for API responses, ensuring that both the frontend and backend use the same type definitions. This avoids mismatches in data structures and simplifies TypeScript's type-checking capabilities across the monorepo.
3. Auth Library for Backend Services: The libs/backend/auth library can provide authentication middlewares and utilities for managing user sessions and permissions, which can be reused across multiple backend services, such as an api and worker application.

Wrapping Up

A well-structured Nx monorepo can significantly enhance the development experience for full-stack applications by promoting code sharing and reducing redundancy. By organizing applications and libraries into distinct, logical folders, teams can achieve modularity, consistency, and scalability. With Nx’s tools for dependency management, affected file tracking, and task optimization, your monorepo can support even the most complex full-stack applications

By adopting the folder structure outlined here, you’ll be set up for scalable development and collaboration as your projects grow.