db4o - database for objects - is a fast client/server Java object database optimised for mobile platforms and other low-resource environments. A footprint of 250 kB saves device memory and allows online-download. ACID transactions keep all data safe in case of unplanned VM stops. Query-By-Example minimizes resource consumption and improves performance. The additional S.O.D.A. query API let's you query your data with all the power of Java. Automatic object recognition permits zero-admin deployment. High integration with the Java programming language omits driver overhead and maximizes speed. All standard Java constructs like arrays and JDK collections are supported. Further functionality includes cascade-on-delete, callback methods and blob storage. WeakReference memory management ensures a constant low memory footprint. No "enhancers": Changes to application classes are not necessary to make objects persistent. db4o supports Java Web Start. db4o is threadsafe and runs in servlet environments like Tomcat.