Currently, the WebKit project consists of six different ports: one for Mac, one for iOS, two for Windows (Apple Windows and WinCairo), and two for Linux (WebKitGTK+ and WebKitEFL). There are some downstream ports as well; unlike the aforementioned ports, downstream ports are, well, downstream, and not part of the WebKit project. The only one that matters for Linux users is QtWebKit.
If you use Safari, you’re using the Mac or iOS port. These ports get frequent security updates from Apple to plug vulnerabilities, which users receive via regular updates.
Everything else is broken.
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