db4o - database for objects - is a fast Java object database optimized for wireless devices. A footprint of 80 kB saves device memory and allows online-download. Query-By-Example minimizes resource consumption and improves performance. Automatic object recognition permits zero-admin deployment. High integration with the Java programming language omits driver overhead and maximizes speed. Changes to application classes are not necessary to make objects persistent. Callback methods allow cascade-on-delete and cascade-on-copy. A benchmark for a performance comparison against relational databases is available with the download. db4o supports Java Web Start. db4o is threadsafe and runs in servlet environments like Tomcat. db4o is free for non-commercial use.