Leonidas is creating a new software package and is making use of the OpenSSL library. What term best describes the library he is using?

The OpenSSL package is a widely used implementation of TLS encryption that is available as an open-source package. It is not commercial off-the-shelf software (COTS). While it might be developed by third parties, it is more accurate to describe it as open source. The library is available as code for free use, but not as a managed service.