Hidden Bar lets you hide menu bar items to give your Mac a cleaner look.

Your personal research assistant
Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.

Ncdu is a disk usage analyzer with an ncurses interface. It is designed to find space hogs on a remote server where you don't have an entire graphical setup available, but it is a useful tool even on regular desktop systems. Ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like environment with ncurses installed.

Airtable makes it easy to organize stuff, people, ideas and anything else you can imagine with your team.

TagSpaces is an open source personal data manager.
It helps you organize and browse your files on every platform.