Download CyanogenMod 10.1 for Galaxy S4 [official]
Steve Kondik (founder of CyanogenMod) is true on his words as he has released the CyanogenMod 10.1 (CM10.1) for the Samsung Galaxy S4, CyanogenMod is one of very popular AOSP (Android Open Source Project) custom ROM around the world, since it’s based on AOSP, it can be used for stock Android experience, this custom ROM packs a lot of customization options to generate a personal interface depending on your choices even it includes many handy Android apps such as T9 dialer app, Apollo music player app, CM File Manager and more.
CyanogenMod for Galaxy S4 is available in nightly builds for just two variants as for that are T-Mobile (SGH-M919) and Canadian (SGH-i337M) variant, but worry not as they’ll hopefully bump up new builds for other variants soon. If you’re unfamiliar with nightly build, it generates a new build on daily basis to bring new features but it’s also important to note that it may also bring bugs.
Since this is very initial and experimental build, you may face bugs that are expected to be ironed out in near future, the developer himself notes that there are a “a few rough edges”.