Two weeks after the release of the 14th version, Apple has recently released the 15th release for Safari Technology Preview. As a reminder, this is still only an experimental version of the next browser that will equip Macs. It is announced as much more stable and more efficient and is aimed more particularly at developers. However, it is also possible for simple users to install it on their computer and take advantage of its functionality.
If this 15 version of Safari Technology Preview interests you, you can already download it here for OS X El Capitan and there for macOS Sierra. And as usual, anyone who already has the previous version (14th release) can update from the Mac App Store.