Analysis of information sources in references of the Wikipedia article "Oracle SQL Developer" in English language version.
Is Oracle SQL Developer Data Modeler free? - Yes.
OWA (Oracle Web Agent) or MOD_PLSQL is an Apache (Web Server) extension module.
SQL Developer Data Modeler is a data modeling and database design tool that provides an environment for capturing, modeling, managing, and exploiting metadata.[...] SQL Developer Data Modeler is a for-cost option of SQL Developer that requires a separate license. However, a free viewer (read-only) version is also available [...]
When you save a database design, the structural information is stored in an XML file (with the extension .dmd)