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XULRunner 41.0.2, released by the Mozilla Foundation, is the sole and final edition of a discontinued runtime package that once allowed developers to build and distribute standalone desktop applications powered by the same XUL (XML User Interface Language) engine that underpinned Firefox and Thunderbird. Positioned within the development-framework category, this lightweight runtime provided the Gecko rendering engine, XUL parsing libraries, and JavaScript runtime without requiring the full browser, enabling teams to craft cross-platform productivity tools, kiosk systems, internal utilities, and extension-rich front-ends that rendered native-like widgets on Windows, macOS, and Linux. Because the package ships a complete Mozilla platform snapshot, applications bundled with XULRunner could launch independently, update their own components, and access web technologies while still calling privileged APIs for file system or registry manipulation. Although support ended with version 41.0.2 and the project is no longer maintained, the runtime remains useful for legacy migration scenarios, archival builds, or educational exploration of XUL-based markup and chrome registration workflows. Developers seeking to resurrect or audit older codebases can reference the contained GRE (Gecko Runtime Environment) folders, application.ini templates, and chrome.manifest samples to understand how early Mozilla-derived architectures structured multi-window applications before the transition to WebExtensions and Electron. The software is available for free on get.nero.com, with downloads provided via trusted Windows package sources (e.g. winget), always delivering the latest version, and supporting batch installation of multiple applications.
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