Free Software for macOS
Vim
Vim dates back all the way to 1991 when Vim's author, Bram Moolenaar released it to the public. Vim is a highly configurable text editor built to enable efficient text editing. The software is released as free and open-source software under the Vim License. Vim is often called a "programmer's editor," as it relies more on customization of shortcuts and makes heavy use of macros that can be combined with muscle memory to achieve maximum proficiency. Vim was designed for use in both command-line interfaces and as a standalone application in a graphical user interface.
HedgeDoc
HedgeDoc, formerly known as CodiMD is an open-source collaborative markdown editor. HedgeDoc provides collaborative features that makes it easy for teams to work together by creating notes, graphs and even presentations in real-time. With HedgeDoc, all you need to get started is to share a link to your co-workers, and they can join you in the process.
Ruby
Ruby is a free and open-source interpreted, high-level, general-purpose programming language. The language was created by Yukihiro "Matz" Matsumoto from Japan in the mid-1990s. Today, Ruby has a friendly and growing community from all over the world and is openly developed and maintained. According to its creator Yukihiro, the language share many similarities with Perl, Smalltalk, Eiffel, Ada, Basic, and Lisp, all of which Ruby was influenced by.
TextMate
TextMate is a powerful and customizable, general-purpose GUI text editor for macOS. TextMate supports a huge varity of programming languages and actions that can be written for any language that can work with stdin, stdout, and environment variables, and for complex interactions. TextMate is released fully open-source under the GNU General Public License.
Apache Mesos
Apache Mesos a free an open-source cluster orchestration platform. It allows you to allocate dynamic resource between applications and enables you to build fault-tolerant and elastic distributed systems. With Apache Mesos, your applications are only aware of the resources of a particular partition or machine they are running on. It also provides an abstract view of all resources used by any application in the system, where you can allocate resource, per application basis. Apache Mesos is battle-tested and industry proven to easily scale to 10,000s of nodes.
DBngin
DBngin is a free , all-in-one database version management tool and database GUI native to macOS. With DBngin you can easily start and manage PostgreSQL, MySQL, Redis & other databases. The friendly user interface allow you to create a database in a single click and browsing, querying and modifying the database through DBngin's GUI Client.
Swarmlet
Swarmlet is a free and open-source, self-hosted Platform as a Service that runs on any single server. It's mainly intended for use with multiple servers, a server cluster / swarm. Swarmlet is inspired by Dokku and brings the same simplicity to Docker Swarm. Swarmlet also uses Traefik v2 and Let's Encrypt to provide automatic SSL and load balancing on your apps.
Gitter
Gitter is an open-source instant messaging and chat room system for developers designed to make community messaging, collaboration and discovery as smooth and simple as possible. Gitter is provided as software-as-a-service and integrates with GitLab and GitHub repositories to make discussion around code even easier. With Gitter, you can can easily create, organise and grow your communities, inviting others to join just in one click. Over 1.5M users across 100K communities use Gitter to discuss code and development progress.
Safari
Safari is a fast and energy efficient web browser developed specifically for the Apple eco-system. The Safari browser provides all necessary tools to browse the web efficiently and comes with built-in privacy features. Safari also integrate well with existing Apple products such as Apple Pay which let's you pay safely online. You can also sync browsing history and bookmarks between macOS and iOS keeping your browsing experience alive across devices.
Ricochet
Ricochet is a communications application that uses the Tor network to reach your contacts without relying on messaging servers. It creates a hidden service, which is used to rendezvous with your contacts without revealing your location or IP address. Instead of a username, you get a unique address that looks like ricochet:rs7ce36jsj24ogfw.