Best open source alternativeness to NHibernate

nHydrate - Conceive, Model, GeneratenHydrate is an object-relational mapping (ORM) solution for the Microsoft .NET platform providing a framework for a relational database to be mapped to .NET objects. It is designed to alleviate the software developers experience writing persistence domains. The model controls database generation, LINQ syntax, API, DAL, etc. Fluent NHibernate - Fluent mapping