Peewee is a minimalistic but expressive ORM library for Python. It comes in a single module and file, but supports SQLite, Mysql and Postgres, and comes with extensive documentation. It simplifies model declarations, result set iteration, and provides a rather pythonic way of query building through operator overloading.
Django is a high-level Python Web-MVC framework for RAD with clean and pragmatic code. It's comparatively fast, integrates moderns security features, and is very scalable. It prefers explicit configuration over implicit conventions, has an object-relational database mapper, autogenerated admin interfaces, flexible regex-based URL dispatching, internationalization features, a custom templating engine or Jinja2, caching, authentication or authorization, a user comment plugin, RSS/Atom and sitemap
Hibernate is a popular Object/Relational Mapper tool for Java, and implements the persistence API. Besides ORM functionality, it provides indexing and search, annotation-based constraints, OGM for NoSQL storage, various tools (mapping editor, console, wizards, database reverse engineering) and a few extensions (Hibernate Shards).
YB.ORM is a object-relational mapper for C++. It was inspired by Hibernate and SQLAlchemy and should be database-independent. It provides C++ code generation for domain objects, which can be synchronized with new table definitions as kept in XML meta files, but also provides JSON serialization. YB.ORM was tested with MySQL, Oracle, SQLite, Firebird, Postgres, MSSQL and can utilize ODBC, SOCI and other drivers.
The Ujorm is an open source Java small library based on a key‑value architecture of domain objects. The framework have got a special ORM module designed for rapid Java development with great performance and a small footprint. The key features are type safe queries, relation mapping by Java code, no entity states, and a memory overloading protection cache. Ujorm provides a module to integration with Apache Wicket to build GUI easy.