
Samsung Galaxy S4
Every official firmware build for SM-S975L, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/S975LUDUAOE4

SM-S947W

SM-S942W

SM-S948U

SM-S890L

SM-S767VL
You can find the firmware on the model: SM-S975L page.
Yes, all firmware files for SM-S975L are 100% official, original, and obtained directly from Samsung servers.
To flash SM-S975L, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-S975L.