Open Source Software for macOS
GIMP
GIMP is a free and open-source raster graphics editor developed by the Free Software Foundation (GNU). The software is a perfect fit for anyone looking for a free and open alternative to Adobe Photoshop. GIMP can be used for photo retouching, image editing and composition. The software is commonly know within the Linux community but is available under the GPLv3+ licenses for macOS and Windows as well.
jEdit
jEdit is a mature programmer's text editor written in Java. The editor is released as free and open source software under the GNU General Public License version 2.0. With jEdit you can enjoy features like auto indentation and syntax highlighting for more than 200 languages. jEdit also provides a Plugin Manager that allows jEdit users to install, upgrade, and remove plugins without leaving the editor.
Disk Inventory X
Disk Inventory X is a disk usage utility for MacOS. Disk Inventory X helps users get an understaning of their computers disk space and how it is uitilized. Disk Inventory X answers this questions by providing an overview of files and folder and their size, with an easy-to-unstand graphical user interface that display disk space using treemaps. Disk Inventory X is released fully free and open-source under the GNU General Public License.
LibreOffice
LibreOffice is a free and open source suite of applications for creating text documents, spreadsheets, presentations and more. With LibreOffice you can open almost any legacy document, and it's the only free and open source office suite available on all major desktop platforms. It features a clean interface and feature-rich tools help you unleash your creativity and enhance your productivity. The suite includes the word processor LibreOffice Writer, the spredsheet LibreOffice Calc, the presentation program LibreOffice Impress, the vector graphics editor LibreOffice Draw, the database management program LibreOffice Base and the math tool LibreOffice Math.
Caddy
Caddy is a powerful, enterprise-ready, open-source web server written in Go. The Caddy provides automatic SSL/TLS cretificates so that your application always is served over HTTPS.
NeoOffice
Specifically designed for macOS, NeoOffice brings a free and open source alternative to popular office suites. NeoOffice is based on OpenOffice and LibreOffice and provides a way for macOS users to view, edit, and save OpenOffice documents, LibreOffice documents, and simple Microsoft Word, Excel, and PowerPoint documents.
Netcat
With Netcat you can read and write data across network connections with the TCP/IP protocol. Netcat is a feature rich networking utility for macOS, Linux and Windows that is designed to a reliable tool that can be utilized by external programs and scripts. Netcat provides intricate tools for netowork debugging, network exploration and connection creation.
Double Commander
Double Commander is a cross-platform open source file manager with two panels side by side. The application takes inspiration from Total Commander and brings new features and ideas to file management. With Total Commander all archives are handled like sub directories and you can easily copy files to and from archives. Supported archive types include ZIP, TAR, GZ, BZ2, XZ, LZMA, 7Z, RPM, CPIO, DEB, RAR and ZIPX.
BlueGriffon
A next-generation Web and EPUB Editor based on the rendering engine of Firefox. The BlueGriffon is a WYSIWYG content editor for the World Wide Web. With BlueGriffon you can edit HTML documents in a what-you-see-is-what-you-get fashion.
Jupyter
The Jupyter Notebook is an open-source web application that allows you to create and share documents that contain live code, equations, visualizations and narrative text. The Jupyter Notebook is primarily used in data science for data transformation and cleaning, numerical simulation, statistical modeling and machine learning.