TypeORM
ORM for TypeScript and JavaScript using decorator-based entity definitions. TypeORM supports Active Record and Data Mapper patterns, multiple databases (PostgreSQL, MySQL, SQLite, MongoDB, CockroachDB), and migrations. Popular in NestJS ecosystem where it integrates deeply with NestJS modules. Older than Prisma but more established in the enterprise TypeScript ecosystem.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
QueryBuilder uses parameterized queries by default — prevent SQL injection. Raw query methods (query()) allow SQL injection if string interpolation is used. TypeORM has had historical vulnerabilities; keep up to date.
⚡ Reliability
Best When
You're building NestJS applications where TypeORM's deep NestJS integration, decorator-based entities, and mature ecosystem are advantages.
Avoid When
You want best-in-class TypeScript type safety for queries — Prisma's generated client outperforms TypeORM's type inference.
Use Cases
- • Define database entities using TypeScript decorators (@Entity, @Column, @ManyToOne) co-located with model code
- • Use with NestJS via @nestjs/typeorm module for seamless repository injection and entity management
- • Build complex queries with QueryBuilder for joins, subqueries, and database-specific SQL features
- • Run database migrations with TypeORM's migration system for schema version control
- • Use Active Record pattern (entity.save()) or Data Mapper (repository.save(entity)) based on team preference
Not For
- • Projects prioritizing type safety over flexibility — Prisma offers better TypeScript inference for generated queries
- • Teams that want schema-first database definitions — TypeORM is code-first with decorators
- • New projects not locked into NestJS — Prisma or Drizzle offer better DX for greenfield TypeScript projects
Interface
Authentication
ORM library with no auth — database credentials in connection config.
Pricing
Free and open source.
Agent Metadata
Known Gotchas
- ⚠ TypeORM requires reflect-metadata polyfill imported FIRST before any TypeORM imports — missing import or wrong order causes 'Cannot read properties of undefined' errors for decorators
- ⚠ DataSource initialization must complete before any repository or entity operations — forgetting to await dataSource.initialize() causes cryptic 'DataSource is not initialized' errors
- ⚠ Eager loading relations with eager: true on @ManyToOne can cause circular reference issues and N+1 queries — use explicit find options instead
- ⚠ TypeORM's find() returns empty array for no results, findOne() returns null — not throwing means agents must check for null explicitly
- ⚠ Migration generation (typeorm migration:generate) reflects schema diffs — running in CI without a database connection requires mock database setup
- ⚠ Decorator metadata requires experimentalDecorators and emitDecoratorMetadata in tsconfig.json — missing these flags causes silent decorator failures
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for TypeORM.
Scores are editorial opinions as of 2026-03-06.