The only (non-J2SE) external library which is sometimes used by JSAMP
is Apache XML-RPC:
xmlrpc-1.2-b1.jar.
Note however that this library is not necessary for using JSAMP,
it is only required if you want to use the Apache XML-RPC implementation.
If you want to use the internal XML-RPC implementation instead,
which is generally recommended, then no extenal libraries are required.