That would be pkgtool
. Pretty much everything in Slackware is installed as a Slackware package, and pkgtool (as well as installpkg and removepkg) are the tools you use to manage them.
By the way, if you compile from source, you need to install checkinstall
. It replaces the make install step of compiling and instead creates a Slackware package and then installs it. Basically it allows you manage your compiled programs as easily as a Slackware package.