From Wikipedia..."PL/SQL Developer, an Integrated Development Environment for developing software in the Oracle database environment, focusses on the development of PL/SQL stored-program units. Allround Automations, based in Enschede in the Netherlands, markets the software."

From Ross...I use PL/SQL Developer from Allround Automations to work with and examine Oracle databases to find APIs and data I need to use when creating reporting using SSRS, SSIS and SSAS. PL/SQL Developer provides facilities to exploer all aspects of any Oracle database and I prefer it to other tools avalible such as TOAD.