Bootstrapping a NestJS API for Personal Finance

Source: Dev.to

Overview

The majority of NestJS tutorials online stop at basic CRUD operations or simple TODO list applications. In this series we’ll move beyond those beginner examples and build a Personal Finance API from scratch—a production‑ready REST API to manage income, expenses, and account types.

Each post is a short 3–4 minute read focusing on one specific aspect of the application. By the end you’ll have a fully functional API that can be extended or integrated with any frontend.

Architecture

• NestJS – backend framework (TypeScript, dependency injection, decorators)
• Supabase – PostgreSQL database hosting and authentication
• Drizzle ORM – type‑safe database queries and migrations
• REST – clear resource modeling

Feature Modules

• auth – user authentication and authorization
• accounts – account types: cash, debit, and credit
• transactions – income and expense tracking
• categories – transaction categorization

We’ll use semantic versioning throughout the series (e.g., v0.1.0 → v0.1.1 → … → v1.0.0).

Bootstrap the NestJS Application

# Install the Nest CLI globally
npm i -g @nestjs/cli

# Create a new project
nest new finance-api

# Choose your preferred package manager (npm, yarn, or pnpm)

The CLI generates a clean project structure with:

• TypeScript configuration
• Basic module, controller, and service
• Testing setup with Jest
• ESLint and Prettier configurations

Project Structure

src/
├── auth/             # Authentication module
├── accounts/         # Accounts module
├── transactions/     # Transactions module
├── categories/       # Categories module
├── common/           # Shared utilities, decorators, guards
│   ├── decorators/
│   ├── guards/
│   ├── interceptors/
│   └── filters/
├── config/           # Configuration module
├── database/         # Database connection and Drizzle setup
│   ├── migrations/
│   ├── schema/
│   └── seeds/
├── app.module.ts
└── main.ts

Supabase Provides

• Managed PostgreSQL database with automatic backups
• Built‑in authentication (email/password, OAuth, magic links)
• Real‑time subscriptions (optional for future features)
• Auto‑generated REST API (we’ll build our own)
• Free tier perfect for development

Why Drizzle ORM?

• Full TypeScript type safety without decorators
• Lightweight and performant (faster than TypeORM)
• SQL‑like syntax that’s easy to learn
• Migration system that’s version‑control friendly
• Perfect integration with NestJS’s modular architecture

Alternative considered: Prisma (great, but Drizzle gives more control over queries and better performance for complex relations).

What You Have So Far

• ✅ A clean NestJS project ready for development
• ✅ Understanding of the overall architecture
• ✅ A clear folder structure to keep code organized
• ✅ Knowledge of why we chose Supabase and Drizzle

Next Steps

Review the code so far:

🔗 Code: [GitHub repository]

💡 Next post: We’ll set up Supabase.