In October 2014, Actian declined to continue to actively pursue and promote the commercial db4o product offering for new customers.

[1] The term object-oriented database system dates back to around 1985, though the first research developments in this area started during the mid-1970s.

In 2008 db4o was purchased by Versant corporation, which marketed it as open-source bi-licensed software: commercial and the GNU General Public License (GPL).

One of its main goals is to provide an easy and native interface to persistence for object oriented programming languages.

db4o contains a function to store any object: SomeClass here does not require any interface implementations, annotations or attributes added.

Rather than using string-based APIs (such as SQL, OQL, JDOQL, EJB QL, and SODA), Native Queries (NQ) allow developers to simply use the programming language itself (e.g., Java, C#, or VB.NET) to access the database and thus avoid a constant, productivity-reducing context switch between programming language and data access API.

LINQ allows the creation of object-oriented queries of any complexity with the benefit of compile-time checking, IDE Intellisense integration and automated refactoring.

db4o also runs with Java ME dialects that support reflection, such as CDC, Personal Profile, Symbian OS, SavaJe and Zaurus.

Depending on customer demand, db4o will also run on dialects without reflection, such as CLDC, MIDP, BlackBerry and Palm OS.

[9] Information can also be retrieved from forums [10] and community additions[11] (articles, translated documentation sources, sample projects etc.).

For commercial users db4o suggests dDN (db4o developer network) subscription with guaranteed 24-hour support and live pairing sessions with the client – Xtreme Connect.

[12] Object Management Enterprise (OME) is a db4o database browsing tool, which is available as a plugin to Eclipse and MS Visual Studio 2005/2008.

db4o public SVN repository is also available for the developers to get the source code and build versions locally with or without custom modifications.