How to take a backup for the 'connection details' in sqldeveloper?

From Sql developer you can export the connections and then easily import them

1. Right click connection.
2. Select Export
3. Browse to provide it a xml file path to export connection. Select Ok.
4. Click Import in connections similarly to export.
5. Select the xml file and all your connections should be imported.

Note : If you are using Connection type as TNS and providing alais then you will have to export tnsnames.ora file separately. Then provide it to sql developer using

Tools -> Preferences -> Database -> Advanced -> Tnsnames directory

The 'oracle sqldeveloper' stores all the connection details in an xml file ie. connections.xml.
If you want to have a backup for the connection details, you will have to navigate to

In windows XP
C:\Documents and Settings\<YourUserName>\Application Data\SQL Developer\systemX.X.X.X.X\o.jdeveloper.db.connection.X.X.X.X.X.X.X\

In Windows 7
C:\Users\<YourUserName>\AppData\Roaming\SQL Developer\systemX.X.X.X.X\o.jdeveloper.db.connection.X.X.X.X.X.X.X\

and take a backup of connections.xml .

Later, if you need to use the same connections on some other machine, you may simply copy the <Reference ...> tags for respective connections.