Safari Technology Preview 238 Released

The Safari Technology Preview program, first introduced in March 2016, allows developers to test features planned for future public releases of the Safari browser. It functions as a standalone application that can be run alongside the current stable version of Safari, enabling direct comparison and testing of in-development WebKit features. Updates to the Technology Preview are typically issued every two weeks through the Mac App Store, providing a regular cadence of the latest bug fixes and feature implementations from the WebKit engine. This allows for early feedback from developers on new web technologies before they are incorporated into the main Safari browser. Release 238 introduces threaded time-based animation resolution, a feature designed to synchronize accelerated animations with scroll-driven ones while running them off the main thread for improved performance. This update also enables CSS Motion Path animations to be accelerated and adds support for the `:open` pseudo-class, which applies to form elements like `<details>` when they are in an open state. This version also addresses specific rendering and security issues. It fixes a potential phishing vulnerability where an internationalized domain name could be displayed as a visually identical legitimate domain in the address bar. Additionally, a performance hang that occurred when rendering tables with a large number of `rowspan="0"` cells has been resolved. The preview is available for macOS Sequoia (version 15), which was released to the public on September 16, 2024. Sequoia introduced features like iPhone Mirroring and the first wave of Apple Intelligence capabilities. It is also compatible with macOS Tahoe (version 26), which was released on September 15, 2025. macOS Tahoe is notable for being the final version of the operating system to provide support for Macs with Intel processors.