Sequelize is one of the most established and widely adopted ORMs for Node.js and TypeScript, providing a promise-based API for interacting with relational databases including PostgreSQL, MySQL, MariaDB, SQLite, SQL Server, Snowflake, Oracle, and DB2. It abstracts away raw SQL by letting developers work with JavaScript objects that represent database records, automatically translating operations into the correct SQL syntax for the target database. Sequelize has been a foundational tool in the Node.js ecosystem for over a decade, powering countless production applications.
Sequelize offers comprehensive features including model definition with automatic table synchronization, data validation and constraints, association handling for one-to-one, one-to-many, and many-to-many relationships, and transaction support with savepoints. It provides migration tooling for managing schema changes without data loss, eager and lazy loading strategies, scopes for reusable query filters, hooks for lifecycle events, and raw query support when the ORM abstraction is insufficient. The v7 release adds full TypeScript support with improved type inference for models and queries.
Sequelize is targeted at Node.js developers building traditional web applications, REST APIs, and enterprise systems who need a battle-tested ORM with broad database compatibility. It integrates well with Express, Fastify, NestJS, and other Node.js frameworks, and its mature ecosystem includes extensive documentation, a large community, and numerous third-party plugins. Sequelize is particularly valuable for teams that need database-agnostic code, allowing them to switch between SQL databases with minimal code changes.
