Apps to Extensible by Plugins/Extensions

Hugo is a lightning-fast static site generator written in Go. It's designed for building websites rapidly, offering a flexible templating system, theme support, and a built-in development server for quick previews. Ideal for blogs, portfolios, and documentation sites.

DJL (Discontinued Jockey Launcher) is a free and open-source game manager written in Python, designed to consolidate your gaming library. It aims to provide a centralized hub for launching games and managing related aspects, supporting various platforms and features for a streamlined gaming experience.

ThinkComposer is a highly flexible visual modeling tool designed for users to create rich, structured diagrams based on their specific domain knowledge. It facilitates the organization and visualization of complex information through various diagram types and hierarchical structures, enabling deep understanding and effective communication of ideas.

UberWriter is a discontinued open-source minimalist text editor designed for distraction-free writing with integrated Markdown support, syntax highlighting, and a focus on simplicity. It provides a clean environment for authors and writers.

Kiwi IRC is a modern, open-source web-based Internet Relay Chat (IRC) client designed for simplicity and ease of use. It allows users to connect to various IRC networks directly through their web browser without needing to install desktop software.

Kohana is an open-source HMVC framework for PHP 5, designed to be swift, secure, and small. Built by a team of volunteers, it emphasizes object-oriented programming, extensibility, and includes robust features for web development.

wxMEdit is a versatile cross-platform text and hex editor, serving as a powerful alternative to the discontinued MadEdit. Built on C++ and wxWidgets, it provides developers and advanced users with robust features for editing text files and binary data.

FluxBB is a lightweight, open-source bulletin board system designed for simplicity, speed, and low resource usage. It offers core forum functionalities with a focus on performance and ease of use, distinguishing itself from more feature-heavy alternatives.

Buildbot is an open-source framework for automating the build, test, and release process of software projects. It operates as a job scheduling system, orchestrating various tasks based on code changes and other triggers.

Babun is a Windows shell with a focus on developers, providing a Unix-like command-line environment powered by Cygwin. It offers a wealth of pre-configured tools and features for seamless development workflows on Windows.

bbPress is a highly focused, minimalist forum software designed for seamless integration with WordPress websites. Developed by the creators of WordPress, it prioritizes speed and simplicity.

Tuleap Open ALM is a comprehensive open-source platform designed for agile project management and software development teams. It integrates various tools like Git, Kanban, Scrum, and issue tracking into a single, unified environment.

PyScripter is a free and open-source integrated development environment (IDE) designed specifically for Python on Windows. It is built using Object Pascal and provides a comprehensive set of tools for efficient Python development, including debugging, code completion, syntax highlighting, and more.

Polymer is a JavaScript library developed by Google for building web applications using reusable custom HTML elements. It simplifies the creation of complex user interfaces by leveraging modern web standards.

Ex Falso is a robust, free, and open-source cross-platform audio tag editor designed for meticulous music library management. It provides powerful tools for editing metadata across various audio formats, ensuring your collection is organized, searchable, and consistent.

Icedove is a robust and adaptable open-source email client forked from Mozilla Thunderbird, offering comprehensive email management, RSS feed aggregation, integrated chat, and extensive customization options through extensions.

Moovida, formerly Elisa, was an open-source, cross-platform media center designed to offer a visually appealing and intuitive interface for managing and playing multimedia content. Providing support for various media formats and streaming capabilities, it aimed to be a central hub for digital entertainment.

OneSwarm was a file-sharing client focused on privacy and anonymity, designed to operate within a darknet or a friend-to-friend network.

MyBB (MyBulletinBoard) is a free, open-source forum platform written in PHP and utilizing MySQL. It provides a robust and extensible solution for building online communities, offering features like integrated spam protection, user management, and a plugin system for customization.

Speed Dial is a versatile browser extension designed to replace your default new tab page with a highly customizable visual dashboard, offering quick access to frequently visited sites, bookmarks, and browsing history for enhanced navigation and productivity.

Psi+ is a robust, cross-platform XMPP/Jabber client tailored for users who prioritize control, privacy, and extensibility. As a development branch of the classic Psi client, it offers advanced features for secure and customizable instant messaging.

rxvt-unicode, often abbreviated as urxvt, is a highly customizable and lightweight terminal emulator known for its performance and extensive feature set provided through plugins. It's a fork of the original rxvt and is a popular choice for users seeking a fast and highly configurable command-line interface.

SynWrite is a comprehensive and free source code editor for Windows, serving as an excellent Notepad replacement with robust features for various programming and web development tasks. It's designed for performance and extendibility, making it suitable for both novice and experienced developers.

Scribes is a free and open-source minimalist text editor designed for programmers and writers who value simplicity and efficiency. It provides a clean interface with essential features like syntax highlighting, autocompletion, and extensibility through plugins, making it a lightweight yet powerful tool for various coding and writing tasks.

WeeChat is a highly customizable, free and open-source command-line based chat client. Designed for efficiency and portability, it supports multiple protocols including IRC and XMPP, making it a versatile tool for connecting to various networks.

Textadept is a powerful, free, and open-source text editor designed for programmers. Focusing on speed and extensibility, it offers a minimalist interface while providing robust features like syntax highlighting, code formatting, and a built-in terminal, all heavily customizable through Lua scripting.

qutIM is a free and open-source, multi-protocol instant messenger designed for connecting to various networks including ICQ, Jabber, Mail.Ru, IRC, and VKontakte. It offers a unified interface for managing multiple accounts and conversations.

ISPConfig is a robust, open-source hosting control panel for Linux, designed for service providers, resellers, and individuals. It simplifies the management of web servers, mail servers, DNS servers, and more, offering a comprehensive suite of tools via a user-friendly web interface.

OpenProject is a powerful, web-based open-source project management software designed for teams of all sizes. It offers comprehensive tools for managing projects, tasks, teams, and communication in one centralized platform. Ideal for organizations prioritizing collaboration, flexibility, and data control.

Xabber is a free and open-source XMPP (Jabber) client for Android. It provides secure and reliable instant messaging with support for various XMPP features, including encryption, group chat, and decentralized communication. Leveraging the open XMPP protocol, Xabber offers a privacy-friendly alternative to centralized messaging platforms.