Application Ermodeller is a free CASE tool for data modelling which is built in Java. This tool supports conceptual and logical data modelling and in the final step, it allows to create physical model that is specific for particular DBMS.

The basic idea is to support development of database via ER modelling in three levels of abstraction:

* conceptual
* logical
* physical

This separation allows to create database model independent on the particular database system. You may create conceptual model and logical model that are independent on any DBMS. Then, you may generate physical model for each DBMS you will use. Afterwards, physical models allows you to generate SQL data definition for your target DBMS.