db4o
db4o (database for objects) is the embeddable open source object database for C#. Features include: fast native C# object persistence, ACID transactions, Native Queries, automatic class schema recognition, small footprint, zero administration.
db4o is the open source object database that enables Java and .NET developers to store and retrieve any application object with only one line of code, eliminating the need to predefine or maintain a separate, rigid data model.
World class innovators deploy the db4o database engine at the heart of next generation data-driven devices and applications to cache user-generated and client-side data, enabling compelling new features and achieving unprecedented performance and flexibility.
Go to http://www.db4o.com/
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