Apple has announced that macOS Sierra, the next iteration of OS X for Mac computers, will be released to everyone for free on Sept. 20. The tech giant has also released the golden master (GM) version of the software to developers on Wednesday.

The GM version of macOS Sierra is the final beta or test version of the new operating system before the final and stable version of the software is released publicly. That being said, the GM version of macOS Sierra comes with most (if not all) of the new features that’s expected to be available on the operating system and this will be the last time that developers will be able to test it out.

macOS Sierra Screenshot of Apple's website showing the release date of macOS Sierra. Photo: Apple

The GM software is now available to download from the Mac App Store, according to 9To5Mac. However, developers will have to get a promo code from Apple’s developer page in order to get the new software. The code will have to be redeemed on the Mac App Store. GM versions of iOS 10, tvOS 10 and watchOS 3 are also available from their respective App Stores.

The biggest addition to Apple’s operating system is the integration of Siri, the voice assistant that’s been on iOS devices for nearly five years now. There’s three ways to bring up Siri on Macs: an icon on the dock, another in the menu bar and a keyboard shortcut.

Like on iOS devices, users will be able to ask Siri for weather information, sports scores or make web searches. Siri is also a lot more useful on Macs because she can also help locate files based on name, dates, tags or titles.

The macOS Sierra also comes with a new Auto Lock feature which lets a user log in to his or her Mac using Apple Watch. A Mac will automatically log in when it detects that the user wearing a registered Apple Watch is nearby.

Apple Pay is also heading to Mac devices with macOS Sierra, although it will only work on the web through the Safari browser. Users will have to click on Pay with Apple Pay on a shopping website and they’ll receive a prompt on their iPhone where they’ll have to confirm the payment with Touch ID.

The only mac computers that will be able to support macOS Sierra are the MacBooks and iMacs no older than the late 2009 models, according to CNET. Mac mini and Mac Pro models from 2010 are also compatible with the new operating system.