WebKit for Developers
Feb 2015: A lot’s happened since I wrote this post two years ago. Chrome forked WebKit and started Blink, Opera adopted Chromium, and node-webkit became nw.js. This post describes a complexity of defining WebKit that doesn’t exist much anymore; with Chrome’s departure the WebKit world is more simple and clear.
WebKit is deployed through iOS Safari and Mac Safari, and the active GTK community leverages WebKit inside the GNOME Platform. Some smaller mobile browsers use WebKit, some Chromium, some use forks of either, and many just use the system WebViews that are both powered by up-to-date version of iOS WebKit and Android Chromium.
The post below is kept intact and represents a snapshot of history in early 2013, rather than the modern WebKit landscape.
For many of us developers, WebKit is a black box. We throw HTML, CSS, JS and a bunch of assets at it, and WebKit, somehow.. magically, gives us a webpage that looks and works well. But in fact, as my colleague Ilya Grigorik puts it…
WebKit isn’t a black box. It’s a white box. And not just that, but an open, white box.
So let’s take a moment to understand some things:
What isn’t WebKit?
How is WebKit used by WebKit-based browsers?
Why are all WebKits not the same?
Now, especially with the news that Opera has moved to WebKit, we have a lot of WebKit browsers out there, but its pretty hard to know what they share and where they part ways. Below we’ll hopefully shine some light on this. As a result you’ll be able to diagnose browser differences better, report bugs at the right tracker, and understand how to develop against specific browsers more effectively.
Standard Web Browser Components
Let’s lay out a few components of the modern day web browser:
- Parsing (HTML, XML, CSS, JavaScript)
- Layout
- Text and graphics rendering
- Image decoding
- GPU interaction
- Network access
- Hardware acceleration
Which of those are shared in WebKit-based browsers? Pretty much only the first two.
The others are handled by individual WebKit ports. Let’s review what that means…
The WebKit Ports
There are different “ports” of WebKit, but allow me to let Ariya Hidayat, WebKit hacker and eng director at Sencha to explain:
What is the popular reference to WebKit is usually Apple’s own flavor of WebKit which runs on Mac OS X (the first and the original WebKit library). As you can guess, the various interfaces are implemented using different native libraries on Mac OS X, mostly centered around