KeyCastr, an open-source keystroke visualizer

Staggeringly powerful macOS desktop automation with Lua

Darwin/macOS emulation layer for Linux

The Git interface you've been missing all your life has finally arrived.

LuLu is the free open-source macOS firewall

Mac app that shows all open files, directories, sockets, pipes and devices in use by all running processes. Nice GUI for lsof.

A window management application (replacement for Divvy/SizeUp/ShiftIt)

A lightweight macOS window and app manager scriptable with JavaScript

NeXTSTEP-like desktop environment for Linux

PEP - Free & Open Source PDF Editor for Mac