Wikipedia
nHydrate 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 drudgery software developers experience writing persistence domains.
nHydrate is free as an open source project on Codeplex.com under the Microsoft Public License (Ms-PL).
nHydrate was originally created in 2003 as a private project to solve the issues with the .NET Framework 1.1. Using ADO.Net Datasets is cumbersome and error prone, so a small generated framework was created to relieve developers of the CRUD work. As a private project it was later inspired by the work of the NHibernate group.
nHydrate was a private project from 2003 until 2009. It was used at various companies in the Atlanta, Georgia, area but never widely released. It was publicly released on September 10, 2009.
nHydrate is built on the .NET Framework 4.0.
From version 5.0 and above, the entire framework has been reworked to use only Entity Framework as it internal data access layer. The modeler is now visual with a main diagram like other modeling products. All code interactions are simply Entity Framework now so there is no learning curve for developers when using the generated output.