Downgrading an to iOS 5 (specifically iOS 5.1.1) is a popular project because it restores the device to its original, fluid performance. Unlike most iOS versions, iOS 6.1.3 and iOS 8.4.1 remain "signed" for the

If you are already on a later version (like iOS 9.3.6) and have jailbroken your device, you can use CoolBooter .

to gain access to Cydia. If you prefer a cleaner base, many users first perform an untethered downgrade to iOS 6.1.3 (which is still signed via OTA) using Legacy iOS Kit 2. Install CoolBooter on your device. Enter the following URL: