AltStore

AltStore is an alternative app store for iPhones and iPads that does not require jailbreaking. Apple only officially allows apps to be installed through the App Store, but AltStore works around this by using your personal Apple developer account, which every Apple ID holder has in a limited form, to re-sign app files and install them on your device.

The setup requires two pieces: the AltStore app on your iPhone or iPad, and a companion desktop app called AltServer running on your Mac or Windows computer. When you want to install an app, AltStore communicates with AltServer over your local WiFi connection, and AltServer handles the actual installation using Apple's standard iTunes sync mechanism. Because apps installed this way expire after seven days (a limit Apple imposes on personal development certificates), AltStore also runs in the background to automatically refresh your installed apps before they expire, as long as your device is on the same WiFi network as AltServer.

The project was originally built primarily to distribute Delta, an all-in-one game emulator for iOS. The code is now publicly available and the author has been working on making it possible for other developers to list and distribute their own apps through AltStore as well.

For developers who want to compile the project themselves, it requires Xcode 15, Swift 5.9, and supports iOS 14 or newer for the phone app and macOS 11 or newer for the desktop companion. The README includes step-by-step instructions for building it, including some manual configuration steps needed when running through Xcode rather than installing via AltServer directly.

The license is AGPLv3 due to some dependencies, though the author explicitly grants anyone permission to use, modify, and distribute the original code without restrictions. There is an FAQ on the AltStore website for common user questions.