Apple has introduced Safari Technology Preview (https://developer.apple.com/safari/technology-preview/), a new version of its web browser aimed specifically at developers. It provides an early look at upcoming web technologies in OS X and iOS including the latest layout technologies, visual effects, and developer tools.
Safari Technology Preview is a standalone app that works side-by-side with the current version of Safari, so you can continue to use and reference the current release. It works with iCloud, so you can access your latest Safari Favorites, bookmarks, and Reading List.
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