RevRatio and most of the plugins are distributed under the General Public License version 2. The google plugin uses googleapi, for which the license can be found here. The google plugin is also subject to an exception to the GPL license (see the bottom of gpl.txt).
Internal database support is provided by hsqldb (see hsqldb license information)


RevRatio was developed during a software project course at Helsinki University of Technology (2004-2005) by Kristian SelÚn, Markus Frilund, Andreas Finne, Thomas Gammals, Erik Ihrcke, Michael Wikberg and Mika Lehtinen for the customer Pietari Laurila.

The goal was to create a powerful free (as defined by FSF) licenced under the General Public License. The software had to be scalable, portable and modular and created in Java.

RevRatio uses plugins both for searching online databases and for entering manual plugins. This means that just about any database or other reference can be used with RevRatio; if a suitable plugin doesn't exist, anybody with some Java programming skills can create one (see plugin development).

RevRatio was planned with multiuser environments in mind, but due to a very limited timeframe, this feature is not yet fully implemented. The missing features include authorization and synchronization. The multiuser requirement led to a server-client design that was implemented with RMI.