[12][13] Its JavaScript engine, JavascriptCore, also powers the Bun server-side JS runtime,[14] as opposed to V8 used by Node.js, Deno, and Blink.

[1] JavaScriptCore was announced in an e-mail to a KDE mailing list in June 2002, alongside the first release of Apple's changes.

[20] According to Apple, some changes which called for different development tactics involved macOS-specific features that are absent in KDE's KHTML, such as Objective-C, KWQ (pronounced "quack") an implementation of the subset of Qt required to make KHTML work on macOS written in Objective C++, and macOS calls.

[22] At one point KHTML developers said they were unlikely to accept Apple's changes and claimed the relationship between the two groups was a "bitter failure".

The article also noted Apple had begun to contact KHTML developers about discussing how to improve the mutual relationship and ways of future cooperation.

[35] In November 2007, the project announced that it had added support for media features of the HTML5 draft specification, allowing embedded video to be natively rendered and script-controlled in WebKit.

[47] WebKit is used as the rendering engine within Safari and was used by Google's Chrome web browser on Windows, macOS, and Android (before version 4.4 KitKat).

As of the first half of 2010, an analyst estimated the cumulative number of mobile handsets shipped with a WebKit-based browser at 350 million.

Apple has also ported WebKit to iOS to run on the iPhone, iPod Touch, and iPad, where it is used to render content in the device's web browser and e-mail software.

Although Safari for Windows was silently discontinued[64] by the company, WebKit's ports to Microsoft's operating system are still actively maintained.

The Enlightenment Foundation Libraries (EFL) port – EWebKit – was developed (by Samsung and ProFusion[76]) focusing the embedded and mobile systems, for use as stand alone browser, widgets-gadgets, rich text viewer and composer.

There was also a project synchronized with WebKit (sponsored by Pleyo)[77] called Origyn Web Browser, which provided a meta-port to an abstract platform with the aim of making porting to embedded or lightweight systems quicker and easier.

[82][83] Web Platform for Embedded (WPE) is a WebKit port designed for embedded applications; it further improves the architecture by splitting the basic rendering functional blocks into a general-purpose routines library (libwpe), platform backends, and engine itself (called WPE WebKit).

The GTK port, albeit self-contained, can be built to use these base libraries instead of its internal platform support implementation.

[48] Following the announcement, WebKit developers began discussions on removing Chrome-specific code from the engine to streamline its codebase.

[citation needed] WebCore is a layout, rendering, and Document Object Model (DOM) library for HTML and Scalable Vector Graphics (SVG), developed by the WebKit project.

The WebKit framework wraps WebCore and JavaScriptCore, providing an Objective-C application programming interface to the C++-based WebCore rendering engine and JavaScriptCore script engine, allowing it to be easily referenced by applications based on the Cocoa API; later versions also include a cross-platform C++ platform abstraction, and various ports provide more APIs.

[citation needed] WebKit passes the Acid2 and Acid3 tests, with pixel-perfect rendering and no timing or smoothness issues on reference hardware.

[37][38] The project evolved into SquirrelFish Extreme (abbreviated SFX, marketed as Nitro), announced on September 18, 2008 further speeding up JavaScript execution.