AltServer AltServer for Windows is the desktop half of sideloading. The app comes back on your home screen, signed with your own Apple ID.
The free desktop tool, with a Mac build next to it.
A jailbreak changes iOS itself. Sideloading leaves iOS alone: four simple pieces do the work, and the first one is why no jailbreak is needed.
iOS only opens an app that carries a signature. The desktop tool signs each IPA with your own Apple ID, so the iPhone accepts it and nothing in the system gets jailbroken. Updates from Apple keep coming as usual.
An IPA with no signature
iOS refuses to open it.
Install it on Windows and connect the device with a cable. Apple's iTunes and iCloud for Windows supply the drivers it talks through.
An IPA is an iPhone app packed as one file. Drop it into the tool and choose the device.
The same steps load an app onto each of them. The device trusts your Apple ID once, in Settings, then the app opens from the home screen.
You find the app you want as an IPA and save it on the PC.
You plug in the iPhone and install it from the desktop tool.
When the signature runs out, you refresh it from the same PC.
It is the program on your computer that puts iPhone apps on your iPhone, including the ones the App Store does not carry.
AltServer is the desktop companion of AltStore, an alternative app store for iPhone and iPad. The desktop side signs an IPA with your Apple ID, sends it to the device and renews the signature before it runs out, from Windows or a Mac.
No. iOS stays untouched and keeps updating; only the app carries your Apple ID signature.
No. The desktop tool has a Windows build, and you pick it on the download page.
Open Settings, General, VPN and Device Management, tap your Apple ID and trust it. The app opens after that.
Its signature ran out. Connect the device and refresh the app from the tool to sign it again.
Pick Windows, plug in your iPhone and load your first IPA.
Pick my Windows download