Open source. Open possibilities.

PlayCanvas is an open-source 3D game engine for browsers, supporting WebGL2/WebGPU, XR, physics, and glTF assets. Ideal for games, visualizations, and interactive apps.

Element is a web and desktop collaboration client built for the Matrix protocol, providing a user interface for secure, decentralized communication.

Paperless-ngx is a document management system that transforms physical documents into a searchable online archive to reduce paper usage.

OpenRCT2 is an open-source re-implementation of RollerCoaster Tycoon 2, the amusement-park construction and management game. It adds modern platform support, an improved interface, better guest and staff AI, more editing tools, raised limits, cooperative multiplayer and some mechanics restored from the original RollerCoaster Tycoon.

AzerothCore is an open-source, modular C++ game server framework for hosting private World of Warcraft servers, recreating the Wrath of the Lich King 3.3.5a gameplay experience.

Cataclysm: Dark Days Ahead is a free, open-source turn-based survival game set in a harsh, persistent, procedurally generated post-apocalyptic world, with scavenging, crafting, vehicles and combat, developed by a large volunteer community.

DevilutionX is an open-source port of Diablo and its Hellfire expansion for modern systems, offering engine improvements, bug fixes and optional quality-of-life features. It still requires game data files from the original release or the shareware version.

Cross-platform open-source MUD client with Lua scripting, triggers, mapping, GMCP, Discord integration, and theming.

Asynchronous HTTP client/server framework for asyncio and Python, supporting WebSockets, middleware, and routing.

melonJS is a lightweight, dependency-free HTML5 game engine for 2D/2.5D games. Features GPU-accelerated rendering (WebGPU/WebGL2/Canvas), Tiled map integration, physics, audio, and 3D mesh support in ~250KB. Runs on all major browsers.

RetroChess is a Chess plugin for RetroShare 0.6 that lets you play chess with RetroShare friends and contacts. It installs as a shared-library extension and adds a chess game window plus chat invitations, and ships with a standalone Qt board debugger for testing chess rules.

Ruffle is an Adobe Flash Player emulator written in Rust, targeting desktop and web via WebAssembly. It supports ActionScript 1, 2 and 3, and offers desktop builds, browser extensions, a web demo, plus scanner and exporter utilities.

Rocket.Chat is a secure, open-source communications platform developed in TypeScript, designed for organizations requiring high standards of data protection and customizable team collaboration.

GDevelop is an open-source, cross-platform, no-code game development software for creating 2D, 3D and multiplayer games for mobile, desktop and the web using an event-based system and modular behaviors.

A framework for jumpstarting production-ready Django projects quickly using Cookiecutter.

OpenRA is a free/libre real-time strategy game engine for early Westwood classics like Command & Conquer: Red Alert, Tiberian Dawn and Dune 2000. It is written in C# with SDL/OpenGL, runs on Windows, Linux, BSD and macOS, and offers mapping, modding and dedicated server tools.

openage is a volunteer project building a free engine clone of the Genie Engine used by Age of Empires and AoE II. It uses original assets (not shipped), and gameplay is currently non-functional while the simulation is reimplemented. C++20, Python, Qt6, OpenGL, nyan modding format.

Tiled is a general-purpose tile map editor for tile-based games such as RPGs, platformers and Breakout clones. It supports maps of any size, arbitrary tile and layer counts, custom properties, and the readable TMX map format with multiple tilesets.

Flame is a Flutter-based open-source 2D game engine. It supplies a game loop, component/object system, effects and particles, collision detection, input handling, sprites and animations, plus optional bridge packages for audio, physics, tiled maps, gamepads and more.