In SQL Developer you have a lot of options when connecting to the database. You can use the TNS entries defined but you can also give the hostname, port and SID or Servicename for instance. PL/SQL Developer doesn’t supply these options, but you can still use them…

In the logonscreen you can choose the database by choosing you TNS entry. But did you know you can put in the complete text of a tnsnames.ora entry here?
So, you can type in:

username: demo
password: <<password>>
database: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=LOCALHOST)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=DEMO)))

But it can be done even simpler:

username: demo
password: <<password>>
database: LOCALHOST:1521/DEMO

Maybe you already knew this and I have known this for a while, but I thought I would write this down anyway. Hope the helps some of you.