Apple has released the second developer beta version of OS X El Capitan 10.11 to Mac users who are part of the registered Apple Developer program.
The updated build arrives as 15A204h and is officially labeled as OS X El Captain Developer Beta 2 1.0, separately, a second beta version of OS X Server 5.0 is also available.
Those participating in the Mac developer programs can find the downloads through the software update function of the Mac App Store, otherwise they can initiate the initial download through the Mac Dev Center website. Note if you wish to build a bootable El Capitan install drive, you will need to download the fresh installer rather than the update.
The developer releases remain intended for advanced users who are building software and testing for the future OS X 10.11 release, developer beta builds are buggy and not aimed at public usage. With that said, Mac users who do wish to run OS X El Capitan Public Beta will be able to do so in the coming month, otherwise the final release will be available this fall.
OS X El Capitan is said to heavily emphasize performance, stability, and refinements, with many under-the-hood changes which should bring welcome improvements to the Mac. Additionally, there are handfuls of new and revised features, including a revised Mission Control, a new split screen view, a new system font, enhancements to Spotlight search, and more.
Additionally, Apple has also released a second beta version of iOS 9, and of Watch OS 2.0, both are also currently exclusive to developers.