SQLAlchemy

SQLAlchemy is the industry-standard SQL toolkit and Object-Relational Mapping library for Python, created by Michael Bayer in 2005. It provides two paradigms: Core (a SQL expression language with schema definition, connection pooling, and type coercion) and ORM (a data mapper mapping Python classes to database tables with attribute-based queries and session-based unit-of-work for change tracking). Features include declarative models, configurable relationship loading (selectinload, joinedload, lazyload), select() query API with full expression language, transaction management via Session, connection pooling with recycling, raw SQL support, and multi-backend support for PostgreSQL, MySQL, SQLite, Oracle, and SQL Server via dialect-specific drivers. As of 2026, the project has over 10,000 stars.