That's true, but Safari uses a closed source JavaScript engine.

Seems to me it doesn't count for much unless the whole browser is Free and Open Source. A single non-Free component is enough for them to sneak in functionality that you don't want.

See also: the VSCodium editor/IDE. Official builds of Visual Studio Code do not correspond to the published Visual Studio Code source-code, as they ship with additional telemetry code. The VSCodium project releases binaries more faithfully based on the Open Source code.

Safari's JS engine is open source: https://trac.webkit.org/browser/trunk/Source/JavaScriptCore

My mistake, thanks. TIL.

Is it used in any fully Free and Open Source browser?

Yes, many. Every WebKitGTK based browser [1] will use JSC, so that includes the "GNOME Web" web browser, Midori, and a host of smaller niche browsers.

[1] https://webkitgtk.org/

Neat. Konqueror uses a different engine, right?

It can. Historically Konqueror used KHTML, however, the default has been changed to QTWebEngine, which is based on Blink i.e. Chromium.

It also supports (supported?) rendering using WebKit, or, you can manually change back to KHTML. However, all recent versions of Konqueror default to WebEngine. https://wiki.debian.org/Konqueror

These browser war threads always attract the worst kind of pundits: ones who have strong opinions but no idea what they're talking about.

> That's true, but Safari uses a closed source JavaScript engine.

No.

These thread always attract the worst kind of commenters: ones who make strong claims without providing any explanation or evidence.

It's good that we agree.

And Webkit itself started a fork of KHTML, if I recall correctly.

Correct. As a former die-hard KDE user, KHTML/Konqueror was my daily browser, until I switched to OS X Tiger. Been using Safari since that. Also for web development.