Mac OS X Softwares to Extensible by Plugins/Extensions

Postbox is a powerful and customizable email client designed for professionals managing high volumes of email. It offers robust features for organizing, searching, and managing multiple accounts efficiently, enhancing productivity through a clean interface and advanced tools.

Firefox Nightly is the bleeding-edge development channel for the Firefox web browser. It provides early access to experimental features, bug fixes, and performance improvements, allowing users to test and provide feedback on the very latest browser technology before it's released to the public. It's ideal for developers, testers, and enthusiasts who want to experience the future of Firefox.

Bluefish is a powerful yet lightweight code editor designed for web developers and programmers. It offers a wide array of features for HTML, CSS, JavaScript, PHP, and many other programming languages, focusing on efficiency and ease of use for building dynamic websites and applications.

Xcode is Apple's integrated development environment (IDE) for macOS, providing a comprehensive suite of tools for building applications for all Apple platforms, including macOS, iOS, watchOS, and tvOS. It offers powerful features like code completion, debugging tools, and a visual interface builder.

QEMU (Quick Emulator) is a versatile and powerful open-source hardware virtualizer and emulator. It allows you to run operating systems and programs designed for different architectures on your existing hardware. Acting as a hosted hypervisor, QEMU provides a virtual machine monitor for executing guest systems.

SRWare Iron is a privacy-focused web browser built upon the Chromium project. It aims to remove tracking functionalities and data transmission features present in the standard Chromium build, offering a more secure and private browsing experience while retaining the familiar user interface and performance of Chrome.

Umbrello UML Modeller is a comprehensive, free, and open-source UML diagram tool. It provides robust capabilities for creating a wide range of UML and other modeling diagrams, supporting developers and designers in visualizing complex systems.

Visual Studio Code (VS Code) is a free, open-source, lightweight yet powerful source code editor developed by Microsoft. It supports a wide range of programming languages and offers robust features like debugging, intelligent code completion (IntelliSense), built-in Git control, and an extensive ecosystem of extensions for enhanced functionality. Available for Windows, macOS, and Linux, VS Code has become a popular choice for developers across various disciplines.

Sweet Home 3D is a comprehensive interior design application that helps users draw house plans, arrange furniture, and visualize their home design in 3D. It caters to individuals and professionals alike, offering a user-friendly interface with powerful features.

OmniGraffle is a robust diagramming and vector graphics application designed for macOS and iOS. It empowers users to create a wide range of visuals including precise flowcharts, complex network diagrams, organizational charts, and intricate illustrations.

Alfred is a powerful productivity application for macOS, designed to streamline common tasks and significantly improve your workflow. It acts as a central hub for launching applications, finding files, performing web searches, and executing complex workflows with keyboard shortcuts and intuitive commands.

PhpStorm is a powerful, commercial IDE for PHP developers, built on the renowned IntelliJ IDEA platform. It offers extensive features for efficient coding, debugging, and project management across multiple platforms.

Komodo Edit is a powerful yet lightweight text editor specifically designed for dynamic programming languages. It offers a comprehensive suite of features for developers working with languages like Python, PHP, JavaScript, and Perl, providing smart editing tools, a customizable interface, and extensibility through plugins.

Jitsi is a free and open-source suite of secure, flexible communication tools. It offers multi-platform support for voice (VoIP), video conferencing, and instant messaging, emphasizing privacy and ease of use with no account required to start a meeting.

Maxthon Cloud Browser is a freeware web browser known for its dual rendering engine (Trident and WebKit) and cloud synchronization capabilities, offering a feature-rich browsing experience with built-in tools like ad blocking, download management, and gesture support.

KDE Plasma is a powerful, versatile, and customizable graphical desktop environment designed for Linux and other Unix-like systems. It offers a modern interface, extensive configuration options, and a wide range of included applications, aiming to provide a user-friendly yet highly flexible computing experience.

IntelliJ IDEA is a powerful Integrated Development Environment (IDE) designed primarily for Java programming, but also supporting a wide range of other languages and frameworks. Renowned for its intelligent code assistance, developer-friendly features, and robust tooling, it accelerates development workflows and improves code quality.

MusicBrainz Picard is a leading open-source music tagger that identifies and organizes your digital music collection using acoustic fingerprints and comprehensive metadata from the MusicBrainz database. It offers powerful features like automatic tagging, file renaming, and plugin support to keep your music library clean and accurate.

Coda is a Mac-exclusive integrated development environment (IDE) designed for web developers. It combines a powerful text editor, built-in file management (including FTP/SFTP/WebDAV), version control integration, and web preview tools into a single, cohesive application.

GNU Emacs is a highly extensible and customizable text editor, renowed for its powerful features and ability to serve as a complete development environment. It is based on the Emacs Lisp programming language, allowing for deep customization and a vast ecosystem of packages.

KVIrc is a versatile and highly customizable graphical IRC client available for Linux, Unix, macOS, and Windows. It is designed to cater to both seasoned IRC users seeking advanced control and newcomers looking for a user-friendly interface to connect to various IRC networks.

NINJA-IDE is a free and open-source, cross-platform integrated development environment specifically designed for Python development. It offers a range of features to improve productivity, including syntax highlighting, code completion, debugging tools, and a built-in terminal. Its extensible architecture allows for customization through plugins and themes.

Zend Studio is a comprehensive Integrated Development Environment (IDE) specifically designed for professional PHP developers. It offers a rich set of tools to streamline the development lifecycle for web and mobile applications.

Edraw Max is a powerful, all-in-one diagramming software for creating professional diagrams, charts, floor plans, network diagrams, and much more. It offers a vast library of templates and symbols for various industries, facilitating efficient visual communication and project planning for individuals and teams.

Redmine is a robust and flexible open-source project management web application designed to help teams manage projects, track issues, and collaborate effectively. It offers a wide range of features, including multi-project support, Gantt charts, time tracking, and extensive customization options through plugins and themes.

Brackets is a modern, open-source code editor specifically designed for web development. Built with HTML, CSS, and JavaScript, it prioritizes a streamlined workflow with its innovative features like Live Preview and inline editors, making front-end development more intuitive and efficient.

Adium is a free and open-source instant messaging client for macOS, designed to connect to multiple chat networks simultaneously. Supporting protocols like Jabber (XMPP), Google Talk, AOL Instant Messenger (AIM), ICQ, MSN Messenger, and Yahoo! Messenger, Adium provides a unified interface for all your conversations.

Open Broadcaster Software (OBS Studio) is a free and open-source cross-platform streaming and recording program. It allows users to capture video from multiple sources, mix audio, create custom overlays, and stream live to platforms like Twitch, YouTube, and Facebook, or record locally for later use.

LibreOffice Calc is a powerful and free spreadsheet application, part of the LibreOffice suite. It offers extensive functionality for creating, editing, and managing spreadsheets, including complex calculations, data analysis, charting, and compatibility with various file formats, including Microsoft Excel.

SketchUp is a powerful 3D modeling software widely used for architectural design, interior design, mechanical engineering, and more. It offers an intuitive interface and a vast library of pre-made models, making it accessible for both beginners and professionals.