How Apple’s Engine Limits Modern Web Development •

What is WebKit?

WebKit is an open‑source browser engine created in 2001 by Apple as a fork of KDE’s KHTML/WebCore. It forms the core of Safari and all iOS browsers (by Apple’s mandate). It supports macOS, iOS, iPadOS, tvOS, and watchOS. WebKit interprets HTML, CSS and JavaScript, rendering web content—but over the last decade, has increasingly lagged behind modern standards.

What is Chromium (Blink)?

Chromium is Google’s open-source browser project whose engine, Blink (a fork of WebKit since 2013), powers Google Chrome, Microsoft Edge, Opera, Brave, Vivaldi, and others on Windows, macOS, Linux, Android, and ChromeOS. It advances rapidly, integrating new CSS & JS features across platforms.

Other Rendering Engines & Key Browsers

EngineBrowsersPlatforms
BlinkChrome, Edge, Opera, BraveWindows, macOS, Linux, Android, ChromeOS
WebKitSafari, iOS browsers (all)macOS, iOS, iPadOS
GeckoFirefoxWindows, macOS, Linux, Android
OtherWebView2 (Edge), EdgeHTML (obsolete), GeckoViewVarious

CMS, CSS/JS & Browser Engine Compatibility

Modern CMS platforms (WordPress, Drupal, Joomla, headless CMS like Contentful) leverage advanced CSS (Flexbox, Grid, aspect-ratio, CSS animations/transitions) and modern JavaScript (ES modules, async/await, Web Animations API). Browser engines vary greatly in their support, testing coverage, and performance.

Why it matters

  • Consistent rendering: Sites must look and function uniformly across browsers.
  • Performance: Heavy reliance on animations, media formats (e.g. MP4, AVIF), and complex CSS demand engine speed and accuracy.
  • Developer experience: Fragmented support forces workarounds, vendor prefixes, polyfills, and testing-slowing down development.

WebKit: Falling Behind?

Despite updates, WebKit consistently lags Chrome’s Blink in adopting modern web standards:

Animation glitches

  • CSS animations flicker on iOS/Safari, especially with keyframes:
    Developers report flickering unless using workarounds like
				
					-webkit-backface-visibility: hidden;
  • Keyframe animations often fail entirely on iOS browsers-even when prefixed-breaking sites that use typing‑cursor or SVG‑animated effects.

Lottie files

Complex JSON‑based Lottie animations often load too slowly-or glitch-on WebKit-based browsers, leading to visual errors or downtime.
Developers note delayed playback, layout shifts, and unsupported features.

Media & high‑res support

  • MP4 and modern codecs sometimes fail or have degraded quality due to missing container/codecs.
  • 120 Hz requestAnimationFrame support is absent in Safari/WebKit, while browsers like Chrome have embraced high‑refresh rates—WebKit may remain limited to 60 Hz
  • Prefixed CSS (-webkit-animation, etc.) still needed—many non‑standard features deprecated.

WebKit, while following an open-source path, remains rooted in architecture from over 10 years ago. It still requires outdated vendor prefixes, mishandles modern animations and codecs, and lacks full support for high‑performance JavaScript and CSS features. As a result, iOS browsers often fail to present the web as designers intended.

Real Developer Complaints

“Keyframe animations not working in any browser on iOS… None of the browsers on iOS seem to work.”

“Lottie file loading slower… making the site glitch.”

“iPhone WebKit CSS animations cause flicker.”

“Embedded Google Maps often fail to load reliably on WebKit-based browsers, sometimes they appear, sometimes they don’t, with no clear pattern.”

These are not isolated cases, they appear repeatedly on StackOverflow, Reddit, GitHub, Apple forums. Many devs report that WebKit breaks smooth animations, media playback, and CMS-driven components.

Why It Matters for CMS & Advanced CSS/JS

  • Modern CMS deliver dynamic content with:
    – Responsive layouts (CSS Grid, aspect-ratio)
    – Rich interactivity (Web Animations API, IntersectionObserver, ES modules)
    – Sophisticated media (WebP/AVIF, Lottie)
  • WebKit limitations mean:
    – Inconsistent rendering on iOS devices
    – Extra development time for fallbacks or polyfills
    – Compromised user experience on Apple hardware
    – Slower adoption of new standards on a key platform

Apple tech is excellent, but the web deserves better. If WebKit doesn’t evolve, Apple risks losing its premium badge in the dev community, and eventually among users.

  • Modern CMS deliver dynamic content with:
    – Responsive layouts (CSS Grid, aspect-ratio)
    – Rich interactivity (Web Animations API, IntersectionObserver, ES modules)
    – Sophisticated media (WebP/AVIF, Lottie)
  • WebKit limitations mean:
    – Inconsistent rendering on iOS devices
    – Extra development time for fallbacks or polyfills
    – Compromised user experience on Apple hardware
    – Slower adoption of new standards on a key platform

No names, no advertising, just honesty from designers and developers on the front line. Want smartphone recommendations based on our daily work and testing? Reach out via our social channels or contact form, we’re always happy to help.

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