Waterfox Classic

Waterfox Classic is a legacy web browser built on an older version of the Gecko platform, targeting users with older operating systems or those who need to run XPCOM and XUL extensions. It provides the same core browsing capabilities as contemporary browsers while maintaining compatibility with add‑ons that rely on these legacy technologies. The software is distributed for macOS, Linux, and Windows and is released under the MPL 2.0 license, allowing anyone to inspect, modify, and contribute to its codebase.

Because it runs on an older Gecko engine, Waterfox Classic does not receive current security updates, and many security advisories remain unpatched. The project warns users to employ the browser at their own discretion, especially in environments where modern security standards are required. This characteristic makes it suitable primarily for niche use cases such as testing legacy web applications or maintaining workflows that depend on outdated extensions.

The open‑source nature of Waterfox Classic encourages community involvement; developers can submit patches, add new features, or create compatible add‑ons via its GitHub repository. Documentation and download links are provided for the three major desktop platforms, and the project invites contributions to improve the browser while preserving its legacy support.