Features
- Promise-based API with transaction support
- Model validation and hooks
- Associations (1:1, 1:N, N:M) with eager/lazy loading
- Migration and seeding tools
Pros
- Mature and battle-tested in production
- Comprehensive feature set for relational databases
- Large community with extensive documentation
Cons
- TypeScript support is an afterthought
- API is verbose compared to modern alternatives
- Query builder generates suboptimal SQL in some cases
Overview
Sequelize is one of the oldest and most established Node.js ORMs, providing a traditional Active Record pattern for working with relational databases. It supports PostgreSQL, MySQL, MariaDB, SQLite, and MS SQL Server with a promise-based API.
Sequelize provides comprehensive features for model definition, validation, associations, transactions, migrations, and seeding. While it was the go-to ORM for Node.js for many years, modern TypeScript-first alternatives like Prisma and Drizzle have gained favor for new projects.
When to Use
Sequelize is appropriate for existing projects that already use it or when you need a traditional Active Record ORM with comprehensive features. For new TypeScript projects, Prisma or Drizzle offer significantly better type safety and developer experience.
Getting Started
npm install sequelize pg pg-hstoreimport { Sequelize, DataTypes } from "sequelize";
const sequelize = new Sequelize("postgres://user:pass@localhost:5432/db");
const User = sequelize.define("User", {
name: { type: DataTypes.STRING, allowNull: false },
email: { type: DataTypes.STRING, unique: true },
});
await sequelize.sync();
const users = await User.findAll();