An Android 4.4 KitKat firmware has leaked for the AT&T variant of the Galaxy S4 on the XDA forums. Released by designgears, the firmware has build number I337UCUFMLD and a build date of January 2nd, which means it's not as new as the latest KitKat firmware that leaked for the international version of Samsung's flagship. However, it should still let users try out Android 4.4 on their devices before it officially rolls out, as long as they're willing to flash pre-release firmware.
Before you proceed to download the firmware, there are a couple of things to note. First, it comes with new bootloaders, which might make it impossible to go back to an Android 4.3 firmware later on. Furthermore, you might not be able to root it until someone comes up with a root hack, and the firmware has an issue that causes the phone to reboot whenever you fire up a video.
Still want to flash? Well, then you can head to the source link below to download the firmware; a one-click version is available for quick flashing, but again, make sure you're okay with test firmware before making a move.