Santa is a binary authorization system for macOS. It consists of a system extension that monitors for executions, a daemon that makes execution decisions based on the contents of a local database, a GUI agent that notifies the user in case of a block decision, and a command-line utility for managing the system and synchronizing the database with a server.
It is named Santa because it keeps track of naughty or nice binaries.
Source code and additional information may be found here: https://github.com/google/santa