Here’s a list of Galaxy S3 stock firmware you can download. These are stock firmwares you can use ODIN to turn your Galaxy S3 completely back to factory. If you just need to return your phone back to stock ROM with root, you can also install Galaxy S3 stock ROMs instead.
U.S. Galaxy S3 stock firmwares
T-Mobile Galaxy S3 Stock Firmware MD5 [Android 4.1.2][Latest]
Sprint Galaxy S3 Stock Firmware MD4 [Android 4.1.2][Latest]
Verizon Galaxy S3 Stock Firmware MF1 [Android 4.1.2][Latest]
Canadian Galaxy S3 stock firmwares
For GT-i9300, check SamFirmware.comNeed Help? Best way to reach me is on Twitter for the fastest response!
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You will need a rooted Galaxy S3 to install all ROM/kernels.
NOTE: PLEASE ONLY INSTALL ROMS INTENDED FOR YOUR VERSION OF GALAXY S3! Otherwise you WILL BRICK YOUR PHONE and I will not be responsible!
First time to rooting and custom ROMs? Please see our Galaxy S3 Root FAQ FIRST! Note: T-Mobile Galaxy S3 ROMs are compatible with Canadian Wind, Mobilicity, and Videotron Galaxy S3s.
AT&T Galaxy S3 ROMs are compatible with Canadian Bell, Telus, and Sasktel Galaxy S3s.