The Safari Technology Preview Release 2 is available for download from the Apple Developer Center, or via the Mac App Store for users who has Release 1 installed on their Mac.
Safari Technology Preview offers developers a sneak peek at upcoming web technologies in OS X and iOS, and allows them to experiment with those technologies in their websites and extensions.
Easy to update. You can update Safari Technology Preview right from the Mac App Store. Updates occur every few weeks and include the most recent additions and improvements to WebKit.
Access powerful developer tools. Use the latest version of the powerful Web Inspector and Responsive Design Mode to modify, debug, and optimize your websites.
Provide feedback. Use Bug Reporter to send feedback directly to Appleabout issues and enhancement requests. Simply select Report an Issue from the Help menu in Safari Technology Preview.
Run side-by-side with Safari. 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.
Surf seamlessly with iCloud. Safari Technology Preview works with iCloud, so you can access your latest Safari Favorites, bookmarks, and Reading List.
The preview browser can be run side-by-side with the existing Safari browser. While it is intended for use by developers, it can be downloaded without the requirement of a developer account.
It should be noted that most users of OS X will likely not want to download and use the new technology preview, as it is designed for use by web developers only. The Develop menu is enabled by default, and stability for day-to-day use is not guaranteed.