As promised back in June, Apple just open-sourced the Swift programming language that developers use to build apps for Macs and iOS devices. While this might not mean much for regular folks who use those apps, for developers, it’s a huge step forward.

Apple is known for creating walled gardens, and that includes the code used to create apps for its ecosystem. Before last year’s rollout of Swift, the company used Objective-C, which was completely closed off—developers couldn’t modify the language at all. That’s not exactly detrimental—apps like LinkedIn, Yahoo Weather, and Clear have switched entirely to Swift for their iOS apps.
But by open-sourcing the language and creating a database at Swift.org, Apple is opening the door for developers to modify Swift to create cross-platform apps—and that could be good news for people who’ve never even used Apple products. Developers can also submit improvements to Swift, which is huge.

Apple isn’t porting Swift to other platforms itself, but developers can find the raw Swift compiler and standard library on Swift.org that will allow them to run code on Linux servers, Android, Windows, and, of course, Apple’s own platforms: iOS, OS X, and newbies watchOS and tvOS.