TypeORM

TypeORM is an object-relational mapper for TypeScript and JavaScript that supports both the DataMapper and ActiveRecord architectural patterns, giving developers the flexibility to choose the pattern that best fits their project structure. The current version 1.0 represents a significant rewrite from the 0.3.x series with improved TypeScript integration, performance optimizations, and a modernized codebase. TypeORM works with MySQL, PostgreSQL, MariaDB, SQLite, Microsoft SQL Server, Oracle, SAP HANA, MongoDB, CockroachDB, and Google Cloud Spanner, using the same entity definitions and query builder API across all supported databases. The library is built from the ground up with TypeScript support, providing complete type safety for database models, query results, and relation loading. Entity definitions use decorator syntax with @Entity, @Column, @PrimaryGeneratedColumn, @OneToMany, @ManyToOne, @ManyToMany, and @JoinColumn annotations, with automatic schema synchronization and migration generation from the command-line interface. The QueryBuilder provides a fluent, type-safe API for constructing complex SQL queries with joins, subqueries, pagination, grouping, ordering, and result caching, with full support for raw SQL expressions when needed. TypeORM supports eager and lazy loading of relations, transactional operations with isolation levels, soft deletes, subscriber hooks for lifecycle events, and custom repository patterns. The cross-platform design runs in Node.js, browsers via WebSQL, React Native, Electron, Ionic, Cordova, NativeScript, and Expo applications. With over 34,000 GitHub stars, TypeORM is one of the most popular TypeScript ORMs, maintained by a team led by Umed Khudoiberdiev with active community contributions from developers worldwide.