PWA on iOS, Part 3: Chrome on iPhone Is WebKit Too. How One Engine Sets the Rules for PWAs on iOS

This is Part 3 of an 8-part series about PWAs on iOS. We've covered the history of the technology and the three ingredients every PWA needs: HTTPS, a manifest, and a service worker. Now it's time to look at the engine all of that runs on, and why, on the iPhone, Apple chose it for you long ago.

A typical bug report from a tester goes something like this: "Works fine on Android. On iPhone we tried Safari and Chrome, and it breaks the same way in both." The tester dutifully opened two browsers and believes two engines are covered, when in fact they tested the same WebKit twice in different wrappers. Chrome on iPhone renders pages with the same system engine as Safari, and so do Firefox, Edge, Brave, and the rest. They differ in toolbars, bookmark sync, and looks, but in every one of them the page is built and run by WebKit, in whatever version shipped with iOS.