Apple is quietly continuing the development of its browser with the release of Safari Technology Preview 251. This experimental version of Safari obviously doesn’t revolutionize the user experience overnight, but it’s far more interesting than a simple maintenance update. Under the hood, Apple is testing an impressive number of WebKit improvements that could eventually make their way into Safari.
Safari Technology Preview has been around since 2016 and essentially serves as a large-scale laboratory. Apple can introduce new web technologies, observe how they behave in real-world conditions, and gather feedback before bringing them to the general public.
Safari Technology Preview 251 is now available
The new release is compatible with Macs running macOS Tahoe and macOS Golden Gate. Those who already use Safari Technology Preview can install the update directly from System Settings > General > Software Update.
The browser can run alongside Safari, so there’s no need to replace your everyday browser just to experiment with the latest technologies. Another useful detail is that, although Safari Technology Preview is primarily aimed at developers, an Apple Developer account is not required to install it.
MacRumors initially reported that Apple had not provided detailed information about the changes. WebKit’s release notes, however, reveal much more: Release 251 incorporates changes to the browser engine between revisions 317935@main and 319386@main.
And it’s quite an extensive list.
CSS and SVG keep evolving
A significant part of the update concerns CSS, with several technologies that will mainly interest web developers.
Safari Technology Preview 251 introduces support for @supports at-rule(…), allowing websites to check whether the browser supports a specific CSS rule. The engine also adds the object-view-box property and new capabilities related to the random() function.
These changes may sound abstract to someone who simply uses Safari to browse websites. Yet these are exactly the building blocks that allow developers to create richer interfaces while reducing the need for browser-specific workarounds.
Apple is also continuing its work on SVG, the vector graphics format widely used across the modern web.
WebKit now supports more references to external SVG resources, including those used with clip-path, markers and other graphical elements. Several issues related to SVG image sizing and value calculations have also been fixed.
Much more than a bug-fix update
WebKit’s release notes show that this version touches numerous components of the engine. The changes therefore go well beyond CSS and SVG: JavaScript, HTML, WebAssembly, WebGPU, WebRTC, Service Workers and Web Extensions are among the areas affected by this Safari Technology Preview release.
That’s precisely what makes these releases worth following.
Safari Technology Preview shouldn’t be considered a conventional “Safari beta.” It’s better described as a window into the direction WebKit is heading. Some features being tested today could appear in a future stable version of Safari, while others may be changed or abandoned before reaching users.
Why Apple maintains two versions of Safari
The strategy makes plenty of sense. Directly modifying the engine of a browser used every day by hundreds of millions of people would be risky. Even a seemingly minor change can cause rendering problems or break a web application.
Technology Preview keeps these two worlds separate.
Safari remains the browser designed for everyday use, while Technology Preview provides an environment for testing emerging standards and deeper WebKit changes under real-world conditions.
For Apple, it also provides valuable feedback from developers outside the company. Problems can therefore be identified long before a technology reaches the public version of Safari.
A glimpse at Safari’s future
To me, Safari Technology Preview 251 is particularly interesting because of the sheer breadth of the WebKit changes. There’s no single spectacular feature you can demonstrate in a few seconds, but rather a long series of technical improvements that gradually move the browser forward.
That’s obviously less exciting than a redesigned interface or a new AI-powered feature. For a browser, though, compatibility with modern web standards, performance and engine stability remain fundamental.
Release 251 shows that Apple continues to move WebKit forward at a steady pace.
What to remember
Safari Technology Preview remains primarily a tool for experimenting with tomorrow’s web rather than a browser everyone needs to install. Release 251 nevertheless demonstrates why the project matters: Apple can rapidly test new technologies without compromising Safari’s stability.
For developers, it’s an opportunity to test websites and applications against upcoming technologies. For everyone else, it provides a fascinating glimpse at features that could gradually make their way into Safari.
FAQ
What is Safari Technology Preview?
It’s an experimental Apple browser designed to provide early access to new technologies being developed for Safari and WebKit.
Does Safari Technology Preview 251 replace Safari?
No. Both browsers can be installed and used simultaneously on the same Mac.
Which Macs support version 251?
This version of Safari Technology Preview is available for macOS Tahoe and macOS Golden Gate.
Do I need to be an Apple developer to use it?
No. Safari Technology Preview is mainly intended for developers, but you don’t need an Apple Developer account to download and use it.
Will all these features eventually come to Safari?
Not necessarily. Technology Preview is an experimental platform. Some technologies may eventually reach Safari, while others could be changed significantly or never appear in their current form.
I'm Clémentine Pithon, and as a technology enthusiast, I write articles to guide you through the world of refurbished devices. My goal is simple: to help you make informed choices, understand the products, and get the most out of them every day. Tips, explanations, and practical advice are at the heart of my articles.
