🏎️AltJIT

AltJIT allows apps sideloaded with AltStore to enable just-in-time compilation, more commonly known as JIT. JIT allows some apps to run significantly faster — or even at all — but iOS does not normally allow apps to use JIT for security reasons. AltJIT is an AltStore-specific workaround that allows you to enable JIT for any sideloaded app whenever you're on the same WiFi as AltServer.

Enable JIT

There are additional requirements for users on iOS 17. Please see the instructions below.

AltStore

1. Open the "My Apps" tab then long-press the app you want to use JIT.

2. Press "Enable JIT" to launch the app, and within a few seconds you should see an AltStore notification saying JIT has been enabled.

AltServer

1. First, make sure that the app you want to use JIT with is running in the foreground of your device.

2. Go to “Enable JIT” > [Your Device], then choose an app you want to use with JIT.

Once enabled, an app can continue using JIT until it is force-quit from the app switcher or purged from memory while suspended in the background.

If you're experiencing issues getting AltJIT to work, be sure to check out our troubleshooting guide.

iOS 17 Instructions (macOS only)

Using AltJIT on iOS 17 is not yet supported for Windows users.

Currently, there are extra steps needed to enable JIT on iOS 17+:

1. Open Terminal on your Mac

2. Install Xcode Command Line Tools with the following command:

xcode-select --install

If you are running macOS Sonoma and see an error that Command Line Tools aren’t currently available, try the following commands instead:

sudo mkdir -p /Library/Developer/CommandLineTools   
sudo touch /Library/Developer/CommandLineTools/.beta  

1. Install Homebrew with the following command:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

1. Install pymobiledevice3 with the following commands:

brew install openssl@3 
python3 -m pip install -U pymobiledevice3==2.30.0 

You must use pymobiledevice3 version 2.30.0 or earlier. Later versions may not be compatible.

1. Connect your device to your Mac via lightning/USB-C. Enabling JIT via WiFi is not yet supported

2. Open AltStore (or any app that requires JIT)

3. AltServer run Enable JIT

Once everything is installed, you can now enable JIT as usual from AltServer, though you may be asked to enter your password.

Enabling JIT on iOS 17 may take up to a minute. To speed up this process, we recommend installing Xcode.

Troubleshooting

"The process 'altjit' failed with code 1. The process 'python3' failed with code 1. stream.tell() failed"

The version of pymobiledevice3 you are using is not currently working with AltServer. Please run the following command to install the last compatible version:

python3 -m pip install pymobiledevice3==2.30.0 construct==2.10.69

"Could not connect to device. The process 'python3' returned unexpected output. Error: No such command 'start-quic-tunnel'."

The version of pymobiledevice3 you are using is not currently working with AltServer. Please run the following command to install the last compatible version:

python3 -m pip install pymobiledevice3==2.30.0 construct==2.10.69

"pymobiledevice3 timed out" (AltServer.ProcessError 0)

If you keep getting this error while trying to enable JIT, you can try extending the default timeout duration by entering the command below in Terminal. Just change "120" to your preferred duration (in seconds).

defaults write com.rileytestut.AltServer JITTimeout 120

"pymobiledevice3 not installed"

Make sure you have followed the above instructions and installed pymobiledevice3. If you're still seeing this error after you've installed it, you can try downloading Xcode and using this command to reinstall pymobiledevice3:

/Applications/Xcode.app/Contents/Developer/usr/bin/python3 -m pip install -U pymobiledevice3

"Could not attach debugger to [app]. [app] is not running"

This means that you tried to enable JIT without the requested app running in the foreground. Make sure to launch the app and have it running before you enable JIT.

If you're still running into issues, you can enable it from AltStore by long-pressing the app in the My Apps tab and selecting "Enable JIT"

"Could not connect to device [Device ID]."

Make sure your device is plugged into your Mac/PC via USB/Lightning until AltJIT has successfully been enabled. Once it's been enabled, you can unplug your device and continue using JIT as long as the app is kept running.