
Samsung Galaxy C7
Every official firmware build for SM-C701X, newest first: one row per build with all regions (CSC) that received it.
Specifications of SM-C7010, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-C900X

SM-C710X

SM-C700X

SM-C500X

SM-C5560

SM-C115W

SM-C900Y

SM-C9008
You can find the firmware on the model: SM-C701X page.
Yes, all firmware files for SM-C701X are 100% official, original, and obtained directly from Samsung servers.
To flash SM-C701X, 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-C701X.