Apps to Extensible by Plugins/Extensions

DokuWiki is a popular open-source wiki software designed for simplicity, versatility, and scalability. It focuses on plain text files for data storage, eliminating the need for a database and offering a lightweight, portable, and easy-to-maintain solution for documentation, knowledge sharing, and collaborative content creation.

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.

Kate, the KDE Advanced Text Editor, is a powerful yet lightweight text editor popular among developers and advanced users. Offering robust features like syntax highlighting, built-in terminal, extensibility via plugins, and comprehensive customization options, Kate caters to a wide range of text editing and coding tasks across platforms.

HexChat is a free and open-source Internet Relay Chat (IRC) client. Built upon the foundations of XChat, it offers a robust platform for connecting to various IRC networks and participating in real-time text-based conversations, making it a favored choice for users seeking a reliable and customizable chat experience.

Empathy is a versatile multi-protocol messaging client designed for text, voice, and video communication across numerous IM networks. It offers features like file transfers, location sharing, and integration with various services, providing a unified communication experience.

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.

Nautilus, also known as GNOME Files, is the official file manager for the GNOME desktop environment. It provides a user-friendly interface for managing files and folders, offering features like file preview, search, and network drive support.

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.

Webmin is a powerful, web-based system administration tool designed for Unix-like systems and Windows. It simplifies common administration tasks through a user-friendly interface, making it accessible for users of various technical levels. It is highly modular and extensible, supporting a wide array of system configurations and services.

Audacious is a highly customizable, lightweight audio player designed for discerning listeners who prioritize sound quality and system resource efficiency. Supporting a vast array of audio formats and extensible via a robust plugin system, it offers a classic, skinnable interface for a personalized listening experience.

Cygwin is a powerful environment that provides a Unix-like shell and command-line tools on Microsoft Windows, enabling seamless execution of many Linux applications and scripts without a separate virtual machine or dual boot.

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.

Code::Blocks is a powerful, free, open-source integrated development environment (IDE) designed for C, C++, and Fortran programming. It offers extensive features for coding, debugging, and building applications across multiple operating systems, catering to both beginners and experienced developers.

Pale Moon is an open-source web browser meticulously crafted for efficiency, ease of use, and customization, built on an independently developed Goanna engine. It provides a traditional browser experience while prioritizing user control and privacy over modern trends like mandatory cloud features and restrictive extension policies.

Miranda IM is a lightweight, open-source, multi-protocol instant messaging client designed specifically for Microsoft Windows. Known for its extensibility and resource efficiency, it allows users to connect to various chat networks simultaneously through a flexible plugin-based architecture.

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.

Shutter is a comprehensive screenshot utility specifically designed for Linux systems. It offers robust features for capturing, editing, and sharing screenshots, making it a versatile tool for developers, designers, and everyday users.

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.

Xfce is a highly customizable, lightweight, and modular desktop environment for Unix-like operating systems, designed for productivity while retaining a visually appealing interface.

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.

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.

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.

GNOME is a popular, user-friendly desktop environment for Linux and BSD systems, focusing on simplicity and productivity, enhanced by a wide range of extensions for customization and functionality.

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.