Riley Testut

Riley Testut is an independent iOS developer based in Dallas, Texas, best known for Delta, a multi-console retro game emulator for iPhone and iPad, and AltStore, an alternative app store for iOS that he co-founded with Shane Gill.

He began working on iOS emulators as a teenager with GBA4iOS and later spent years building Delta outside the App Store, distributing it through AltStore, which sideloaded apps using a developer account. When the EU's Digital Markets Act opened iOS to alternative marketplaces, AltStore PAL launched in Europe as one of the first approved third-party app stores, and Delta went on to top the App Store charts after Apple allowed emulators globally in 2024.

Testut funds much of his work through Patreon, which AltStore uses to let supporters unlock beta builds and paid apps such as the clipboard manager Clip. He has also been a vocal voice on App Store policy for independent developers.