Sequelize

sequelize.org

Modern, promise-based ORM (Object.

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Database

Overview

Sequelize is a modern, promise-based ORM (Object-Relational Mapping) tool for Node.js that supports multiple SQL databases including Postgres, MySQL, MariaDB, SQLite, Microsoft SQL Server, Oracle, Amazon Redshift, and Snowflake. It provides a TypeScript-first approach with strong typing support and follows Semantic Versioning.

The library features solid transaction support, model associations with eager and lazy loading, read replication, soft deletion, migrations, and lifecycle hooks. Sequelize works with both new projects and existing databases, offering automatic table synchronization and flexible querying capabilities through both ORM methods and raw SQL when needed.

Getting started is straightforward: install the package, define your models using DataTypes, and begin persisting and querying data. The project is actively maintained with v6 as the stable release and v7 in alpha, supporting modern Node.js versions.

Key features

  • Multi-database support (Postgres, MySQL, SQLite, MariaDB, SQL Server, Oracle, Redshift, Snowflake)
  • Promise-based and async/await compatible
  • Strong TypeScript support with type inference
  • Model associations and eager/lazy loading
  • Transaction support
  • Soft deletion (paranoid mode)
  • Database migrations
  • Lifecycle hooks
  • Read replication
  • Raw SQL query support
Pros
  • Supports multiple SQL databases with unified API
  • Excellent TypeScript integration with type safety
  • Comprehensive documentation and tutorials
  • Flexible for both new and existing databases
  • Strong community support via Slack and GitHub
  • Automatic table synchronization available
Cons
  • Steeper learning curve for complex associations
  • Performance overhead compared to raw SQL for some queries
  • v7 is still in alpha, not production-ready
  • Requires manual driver installation for each database
Use this if
You need a robust, multi-database ORM with strong TypeScript support, require complex data relationships, or want to work with both new and legacy databases using a unified API.
Skip this if
You need a production-ready v7 release, prefer lightweight query builders over full ORMs, or require the absolute highest performance for simple CRUD operations.

Best for

Building Node.js applications with SQL databasesTypeScript projects requiring type-safe database accessApplications needing complex data relationships and associationsProjects requiring transaction support and data integrityMigrating between different SQL database systems

Alternatives

TypeORMPrismaKnex.jsMikro-ORMDrizzle ORM

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