iOS 4 originally appeared nearly 10 years ago as Apple’s first mobile operating system to drop the iPhone OS naming convention. An 18-year-old developer has now lovingly recreated iOS 4 as an iPhone app, and it’s a beautiful blast from the past. If you never got the chance to use iOS 4, or you’re a fan of the iPhone 3G, OldOS almost flawlessly pulls off the experience of using an iPhone from a decade ago.

OldOS is “designed to be as close to pixel-perfect as possible,” says Zane, the developer behind the app. It’s all built using Apple’s SwiftUI, so it includes buttery smooth animations and even the old iPhone home button that vibrates with haptic feedback to make it feel like a real button.

Apple’s built-in iOS 4 apps have also been recreated here, and it’s a real flashback to the skeuomorphic days of the iPhone whenever they launch. Photos lets you view your existing camera roll as you would have 10 years ago, while Notes transports you back to the yellow post-it notes of yesteryear.

The only apps that don’t work as you might expect are Messages and YouTube. Apple used to bundle YouTube directly into its operating system, and the developer behind OldOS says there are “still some major issues with YouTube” and Messages that they’re working to fix.

Everything else is mostly flawless. and you can even browse the web in the old UI of Safari. The App Store also list apps that will redirect you to the modern store to download and install. There are some things that simply don’t work, including folders and no jiggling to rearrange home screen apps.

We’ve seen this type of nostalgic app appear on the iPhone before. Rewound launched in the App Store back in December 2019, turning an iPhone into an iPod. Apple quickly pulled the app a few days later, citing store violations.

This latest OldOS app is available on Apple’s TestFlight service, which is typically used to distribute beta versions of apps. That means it probably won’t last long before Apple takes exception, so grab it while you can. Zane has also published the source code for the entire project on GitHub, so if you’re willing to compile it in Xcode then it will live forever.