There's something new in the area for developers, especially those more interested in the web.
Safari Technology Preview
Safari is the best way to view websites on the iPhone, iPad and Mac. Safari Technology Preview gives you an early look at the next web technologies on OS X and iOS, including the latest layout technologies, visual effects and development tools so you can have data on how they are implemented and provide an even better experience for users on all Apple devices.
By installing Safari Technology Preview you will have access to the latest web-focused technologies for OS X and iOS, in a simple and easy way even to update, since everything happens through the Mac App Store. In addition, you will have access to powerful development tools, the possibility to send feedback to Apple, compare your work side by side in the Safari Technology Preview and in the current Safari (since both are different apps), browse with full integration with iCloud ( your favorites, Reading List, etc. great difference in relation to compilations nightly WebKit) and more.
The Safari Technology Preview can be downloaded from this page.