Safari 26.4 Drops Major Web Technology Updates: CSS Grid Lanes, WebTransport, and Keyboard Lock API

Breaking News — Apple’s WebKit team today released Safari 26.4, a sweeping update that delivers 44 new features, 191 bug fixes, and one deprecation. The release brings long-anticipated capabilities to the web platform, including CSS Grid Lanes for masonry-style layouts, WebTransport as a modern alternative to WebSocket, and the Keyboard Lock API for enhanced keyboard shortcut control.

Key Features

CSS Grid Lanes finally brings native masonry-style layouts to the web, enabling developers to build rich visual galleries and flexible grids without workarounds. “It’s a long-awaited solution for building rich visual galleries and much more,” the WebKit team said in a statement.

WebTransport offers a low-latency alternative to WebSocket, promising better performance for multiplayer games, live collaboration tools, and video conferencing. “WebTransport opens the door to low-latency experiences like multiplayer games and improved video conferencing,” a WebKit engineer noted.

The Keyboard Lock API gives web apps more control over keyboard shortcuts, allowing full-screen applications to capture keys that were previously reserved by the browser. This feature is expected to improve productivity tools and interactive web apps.

Developer Feedback Drives Changes

The release reflects 2025 developer survey results, where developers asked for more time to catch up with new features and demanded consistent cross-browser behavior. “We hear you loud and clear,” the WebKit team stated. “You asked for browser engineers working on WebKit to help you by squashing bugs and closing gaps in spec coverage.”

Most features in Safari 26.4 are not entirely new; many update existing features to align with the latest web standards. For example, WebKit originally shipped the CSS min() and max() functions in 2018, nearly two years before any other browser. However, until now, these functions could not be used inside the HTML sizes attribute for responsive images. Safari 26.4 removes that limitation.

Bug Fixes and Layout Engine Rewrite

WebKit engineers fixed hundreds of bugs across the platform, with deep improvements to SVG, Tables, MathML, and CSS Zoom. The multi-year rewrite of the layout engine continues: Blocks-in-inline layout is now complete, work on Flexbox carries on, and a rewrite of CSS Grid has begun.

“We are continuing our multi-year rewrite of the layout engine,” the team confirmed. “Blocks-in-inline layout is complete in Safari 26.4, work on Flexbox continues, and we’ve now begun rewriting CSS Grid.”

Background

WebKit is the browser engine powering Safari and all web views on Apple platforms, including iOS, iPadOS, macOS, visionOS, and watchOS. Safari updates are released periodically to improve performance, security, and web standards compliance. Safari 26.4 represents a significant step in addressing long-standing developer requests and aligning with emerging web standards.

What This Means

For web developers, Safari 26.4 reduces the need for third-party libraries and polyfills. CSS Grid Lanes alone can replace many JavaScript-based masonry solutions. WebTransport delivers lower latency for real-time apps, and the Keyboard Lock API enables more immersive web experiences. The focus on bug fixes and spec compliance means fewer cross-browser inconsistencies, giving developers more confidence in building for Safari.

“We care deeply about the experience people have when using Safari,” the WebKit team emphasized. “And we care about the experience people have when using any of the millions of iOS, iPadOS, macOS, visionOS, and watchOS apps that rely on web content.”

How to Report Issues

The WebKit team encourages developers to test their sites in Safari 26.4 and report any remaining bugs at bugs.webkit.org. “If something has been bothering you, it’s worth testing in Safari 26.4 to see if it’s been fixed,” the team said. “When multiple websites signal that something needs fixing, that helps.” Developers are asked to include links, code snippets, or reduced test cases to help prioritize fixes.

This story is developing. More details on individual features will follow.