LuLu is the free open-source macOS firewall

MacOS system extension that allows applications to pass audio to other applications. Soundflower works on macOS Catalina.

A Core Audio based streaming audio player for iOS and macOS

iOS and macOS SDK for communicating with OAuth 2.0 and OpenID Connect providers.

MacOS system extension that allows applications to pass audio to other applications.

Google Toolbox for Mac

TeX Live Utility, a Mac OS GUI for the TeX Live Manager

MacOS system extension that allows applications to pass audio to other applications.

iOS Memoji editor ported to run on macOS through Catalyst

Example for using iOS's private frameworks to create Animoji/Memoji in an app

R GUI for macOS

A template for generating an Xcode project for a macOS app using Briefcase